USMLE pediatry basic 2

107) An 18-month-old male infant is brought to the office by his parents for a follow-up visit. He has a congenital condition that started at the age of 6 months with repeated vomiting and hypotonia, and progressively evolved into choreoathetosis, spasticity and dystonia. Over the past month, he has started biting his hands and arms, pinching himself and banging his limbs against the wall. His family history is unremarkable. On examination, he has several scars, cuts and bruises over his arms and hands. His uric acid levels are elevated. What is the most likely deficient enzyme in this patient?

108) A 16-day-old infant presents with fever, irritability, poor feeding, and a bulging fontanelle. Spinal fluid demonstrates gram-positive cocci. Which of the following is the most likely diagnosis?

109) A 16-year-old boy presents to the emergency center with a 2-day history of an abscess with spreading cellulitis. While in the emergency center, he develops a high fever, hypotension, and vomiting with diarrhea. On examination you note a diffuse erythematous macular rash, injected conjunctiva and oral mucosa, and a strawberry tongue. He is not as alert as when he first arrived. This rapidly progressive symptom constellation is likely caused by which of the following disease processes?

110) An 18-month-old child presents to the emergency center having had a brief, generalized tonic-clonic seizure. He is now postictal and has a temperature of 40C (104F). During the lumbar puncture (which ultimately proves to be normal), he has a large, watery stool that has both blood and mucus in it. Which of the following is the most likely diagnosis in this patient?

112) The mother and father of a newborn come in for the 2-week check-up. The mother complains of “colic” and asks if she can switch to goat’s milk instead of breast milk. Which of the following should be your main concern about using goat’s milk instead of breast milk or cow’s milk?

115) A 4-day-old infant is brought to the physician for an outpatient follow-up visit. The mother's pregnancy and delivery were uncomplicated. The infant weighed 3.4kg (7 .5 lb) and was 19 in (48.2 cm) long at birth. He did well in the newborn nursery and was discharged from the hospital on day 2 of life. Today his mother reports that he is exclusively breastfed, and nurses for 10 minutes every 3 hours. He has 3-4 wet diapers a day, and has not had a bowel movement for two days. On examination, he weighs 2.95 kg (6.5 lb) and is 19 in (48.2 cm) long. He appears jaundiced on the face and chest. The remainder of the physical examination is unremarkable. Laboratory values are shown below. Total bilirubin 15 mg/dl, direct bilirubin 1 mg/dl, Infant's blood type O positive, Mother's blood type A positive. Which of the following is the most likely cause of this infant's hyperbilirubinemia?

116) A 10-year-old presents with 2 months history of heavy menstrual-like bleeding. Menarche occurred 6 months ago and this first menses consisted of spotting for 3-4 days without cramps. Subsequent periods were light in flow but lasted 6 to 8 days. Which of the following is the most likely cause of her bleeding?

117) A 25-year-old woman comes to your office for counseling. She says that her husband has cystic fibrosis, and that she has no family history of this disease. They are planning to have a child. She wonders what the probability is for their baby to have cystic fibrosis. Which of the following is your best response in this situation?

118) An awake, alert infant with a 2-day history of diarrhea presents with a depressed fontanelle, tachycardia, sunken eyes, and the loss of skin elasticity. Which of the following is the correct percentage of dehydration?

119) A newborn infant is brought to the nursery for evaluation after delivery. The mother reports that the pregnancy was uncomplicated, but she had only two prenatal visits. The infant was born via normal spontaneous vaginal delivery and required no resuscitation. The infant has hepatosplenomegaly on examination. While in the hospital, the infant requires treatment for anemia and hyperbilirubinemia. On subsequent examinations, the infant has clear rhinorrhea and ulcerative lesions on his feet. Which of the following congenital infections is most likely in this patient?

120) A 17 -year-old boy is brought to the emergency department by his father after the boy began threatening him at home. Over the last several months, the father reports, the boy has been increasingly abusive. He was recently involved in a fist fight at school. The boy states that there is nothing wrong. He is otherwise healthy. He denies alcohol use, but does admit to occasional marijuana use. On examination he has acne on his forehead and back and his hairline is receding. There is palpable tissue underneath his nipples bilaterally Heart and lung exams are normal. What substance is this boy most likely abusing?

121) A 16-year-old African American male with sickle cell anemia presents complaining of a 1-week history of exertional dyspnea, fatigue, and generalized weakness. He denies fevers, chills, night sweats, or cough. His only medication is oxycodone for chronic pain. On physical examination, he weighs 68 kg (150 lbs) and is 168cm (66 in) tall His temperature is 36.7C (98F), blood pressure is 120/70 mm Hg, pulse is 76/min, and respirations are 18/min. All organ systems appear normal Laboratory studies show: Hematocrit 20%, Mean corpuscular volume 110 fl, Reticulocyte count 1.0%. Which of the following is the most likely mechanism underlying these findings?

122) In the 2nd week of life, a previously healthy newborn develops diarrhea. The stools are watery and voluminous and continue even when the infant is fasting. Which of the following is the most likely pathogen?

123) A 17-year-old girl presents to the office with a 5-day history of a malodorous vaginal discharge. She is sexually active and uses condoms for sexual intercourse. On examination, a thin, white discharge is seen. A "fishy" odor is produced when KOH is added to the discharge. The vaginal fluid has a pH of 5. Which of the following is the most likely finding on a microscopic examination of the vaginal fluid?

124) A 20-month-old male is brought to ER with high fever, confusion and a skin rash suggestive of measles. He has a history of recurrent respiratory infections over the last 6 months. The patient's family has recently emigrated from a rural Russian province. Which of the following forms of vitamin supplementation should be considered in this patient?

125) A 3-year-old male is brought to the emergency department for evaluation of right neck swelling. His parents noticed a lump on his right neck yesterday, which has since increased in size and is now erythematous and tender. He has been previously healthy except for mild upper respiratory tract symptoms last week. His temperature is 38C (100.4F), pulse is 90/min, and respiratory rate is 25/min. On examination, he is nontoxic appearing. A 5-cm anterior cervical lymph node is palpated on the right side. It is poorly mobile, warm, erythematous, and tender to palpation. There is no fluctuance or induration. What is the most likely organism causing these symptoms?

126) A 5-month-old infant is brought to the office for the evaluation of persistent vomiting, failure to thrive, and developmental delay. His antenatal and postnatal histories are not known to his Caucasian foster parents, who adopted him when he was 4 months old. The physical examination reveals an infant with blonde hair, fair skin and blue eyes. His urine has a peculiar musty odor. His plasma phenylalanine level is 40 mg/dl and tyrosine level is normal. His urinary phenylpyruvic and a-hydroxy phenylacetic acid levels are both increased. What is the most likely etiology of this child's symptoms?

127) A 2 1/2-year-old child is evaluated by a neurologist because of difficulty walking. Neurological examination documents ataxia and mental retardation. The neurologist notes the presence of multiple telangiectasias involving the conjunctiva, ears, and antecubital fossae. The child also has a history of multiple respiratory tract infections. Immunoglobulin studies on the child would most likely demonstrate an absence of which of the following?

128) A premature neonate with respiratory distress syndrome is maintained on mechanical ventilation in a neonatal intensive care unit. Two weeks after delivery, the nurses in the intensive care unit notice that higher ventilation settings are needed and that more secretions are being suctioned from the endotracheal tube. A chest x-ray film shows questionable new infiltrates. Which of the following is the most likely pathogen?

129) A 3-year-old boy is brought by his father to the Emergency Department with fever, headache and neck pain that developed over the past several hours. The father states he is not the birth father, and that he and his wife adopted the boy at 18 months of age after his birth mother abandoned him. Physical examination reveals a lethargic male with a temperature of 39.7 C (103.5 F). There is photophobia, and mildly injected conjunctiva are appreciated. Pupils are equal and reactive and funduscopic examination is unremarkable. The patient has neck stiffness with a positive Kernig's sign. A complete blood count reveals a leukocyte count of 24,000/mm3 with 64 segmented neutrophils and 25 bands. A lumbar puncture is performed that reveals elevated CSF pressure, decreased glucose, and elevated protein. A Gram's stain shows gram-negative pleomorphic rods. There is no growth on blood agar. Growth on chocolate agar reveals white colonies. Which of the following is the most likely pathogen?

130) A 2-week-old boy in the neonatal intensive care unit had a birth weight of 1200 g. Ultrasound of the head reveals grade II intraventricular hemorrhage and periventricular leukomalacia. An ophthalmologic examination reveals retinopathy of prematurity of both eyes. In addition, a hearing screen demonstrates bilateral hearing deficits. Which of the following is the most important determinant of this child's neurodevelopmental outcome?

131) A 9-year-old boy is brought to the pediatric clinic by his mother, who noticed that the left side of his mouth has started to droop over the past several days. In addition, he is unable to close his left eye completely and complains of it burning. Review of systems reveals a cold approximately two weeks ago and recent decreased taste sensation. Physical examination reveals a well-nourished male with normal vital signs. There is left eye ptosis and mild erythema of the left conjunctiva. His smile is asymmetrical on the left. Laboratory evaluation, including a complete blood count and chemistry profile, are normal. Which of the following infections is most closely associated with this patient's condition?

132) A 6-week-old child arrives with a complaint of “breathing fast” and a cough. On examination you note the child to have no temperature elevation, a respiratory rate of 65 breaths per minute, and her oxygen saturation to be 94%. Physical examination also is significant for rales and rhonchi. The past medical history for the child is positive for an eye discharge at 3 weeks of age, which was treated with a topical antibiotic drug. Which of the following organisms is the most likely cause of this child’s condition?

133) A 12-year-old girl comes to the physician for an annual examination. She has been in good health for the past year and has no complaints. She began having menses this year and, after a few irregular cycles, is now having a monthly period. Past medical history is significant for multiple episodes of otitis media as a child. Past surgical history is unremarkable. She takes no medications and has no known drug allergies. Physical examination is unremarkable. If not currently immune, which of the following immunizations should this patient most likely receive?

134) An infant is brought to the office for health maintenance visit. On examination, the infant turns when her name is called. She is able to say "mama." Her mother mentions that she also says "dada" at home. She is able to look for her mother when she gets frightened. She also waves bye-bye to the doctor when the doctor steps out of the examination room. What age of this child is most consistent with these developmental milestones?

135) A 4-year-old male is brought to the physician with fever and headache. His symptoms began two days ago with low-grade fever, cough, and congestion. Last night, he developed a temperature of 102 F (38.9 C) and became fussy and less active. Today, he is crying and complaining of a headache. His parents report that he has vomited twice today. In the office, his temperature is 102.5 F (39 C), pulse is 110/min, and respiratory rate is 20/min. On examination, he is irritable and shows signs of photophobia. His oropharynx is erythematous. Nuchal rigidity is present and when the neck is flexed, the patient flexes his lower extremities. The remainder of the physical examination is normal. Lumbar puncture is performed and the results are shown below. CSF: Glucose 60 mg/dL, Protein 80 mg/dL, RBC 10/mm3, WBC 100/mm3, Neutrophils 10%, Lymphocytes 70%, Monocytes 20%, Gram stain negative. Which of the following organisms is most likely responsible for this patient's presentation?

136) A 12-year-old boy is brought to the emergency department with a temperature of 39.1 C (102.4 F) at home, difficulty speaking, and odynophagia for 2 days, Physical examination reveals marked erythema of the right tonsil pillar and edema of the uvula with deviation to the left. In addition to anaerobic bacteria, which of the following organisms is most likely to be isolated from a tonsillar pillar aspirate?

137) A neonate is noted to have many abnormalities, a number of which are located in the midline. The infant has cleft lip and cleft palate. His eyes are very small and have fissures of the iris, shallow supraorbital ridges, and slanted palpebral fissures. He is deaf, and the ears are low set and malformed. Each hand has six fingers and a simian crease. Which of the following congenital abnormalities of the brain is particularly likely to be present in this infant?

138) A 4196 g (9 lb 4 oz) infant is delivered via vaginal delivery to a 31-year-old mother with gestational diabetes. The delivery was complicated by shoulder dystocia. He is taken to the newborn nursery where his initial plasma glucose level is 20 mg/dL. The initial spun hematocrit is 65%. Which of the following congenital anomalies is this baby most likely to have?

139) A 24-month-old girl is brought to the pediatrician's office for evaluation because her mother noticed a yellowish discharge on the girl's underwear for the past 3 days. She had no fever, but her mother said she has been fussier recently. On physical examination, the girl is appears excessively anxious about contact with the physician. Her introitus is inflamed, and the hymeneal edge is jagged at the 8 o'clock position. A vaginal culture is taken. Which of the following organisms, if isolated from the vaginal vault, would constitute the most definitive evidence of sexual abuse?

140) An 8-month-old previously preterm infant with bronchopulmonary dysplasia presents to the emergency department with lethargy. His regular medications include furosemide and spironolactone. His temperature is 37.4 C (99.3 F), blood pressure is 68/32 mm Hg, pulse is 110/min, and respirations are 10/min. He has poor skin turgor and dry mucous membranes. Laboratory chemistry evaluation reveals: sodium, 131 mEq/L; potassium, 3.0 mEq/L; chloride, 84 mEq/L; bicarbonate, 38 mEq/L; blood urea nitrogen, 36 mg/dL; and creatinine, 0.4 mg/dL. An arterial blood gas shows pH, 7.52; PaCO2: 49 mm Hg; and PaO2: 92 mm Hg. Which of the following is the most likely explanation for these findings?

141) An 8-year-old boy with sickle cell disease presents with left leg pain and a high fever. He has been refusing to walk since yesterday. On physical examination, his temperature is 39.8 C (103.6 F), blood pressure is 122/68 mm Hg, pulse is 102/min, and respirations are 20/min. His left femur is tender to palpation 3 cm above the left knee, and there is marked soft tissue swelling. A plain film of his left leg is normal. A bone scan shows increased uptake around the metaphysis of the left femur. Which of the following is the most likely pathogen?

142) A 10-year-old male fell while riding his scooter down a steep hill. In the Emergency Department, his injuries included a fractured wrist and a lacerated spleen, which required surgical removal. Two years later he is diagnosed with bacterial pneumonia. Which of the following bacterial agents is the most likely pathogen for this patient's pneumonia?

143) A 10-year-old boy was healthy until about 10 days ago when he developed 7 days of fever, chills, severe muscle pain, pharyngitis, headache, scleral injection, photophobia, and cervical adenopathy. After 7 days of symptoms he seemed to get better, but yesterday he developed fever, nausea, emesis, headache and mild nuchal rigidity. Cerebrospinal fluid (CSF) shows 200 white blood cells (WBC) per microliter (all monocytes) and an elevated protein. Correct statements about this infection include which of the following?

144) A 12-year-old African American boy is brought to the office due to a 2-day history of high-grade fever and chills. He was apparently well before the onset of fever. He has no bone pain. He has sickle cell disease and has had 4 hospitalizations for painful crises and one episode of osteomyelitis. His blood pressure is 90/60 mm Hg, pulse is 100/min, respirations are 22/min and temperature is 38.9 C (102F). He appears drowsy. His laboratory report shows a total WBC count of 16,000/mm3 with 12% bands and Hb of 9.0 g/dl. Which of the following is the most likely cause of this patient's condition?

145) A 13-year-old comes to your office expressing concern about his height. He had first seen you a year prior for his routine checkup and a preparticipation sports physical for soccer (see growth curve). Now in the eighth grade, all of his friends are taller than he is, and he is at a disadvantage on the soccer field playing against much larger boys. After obtaining height information from his parents shown here, you order a skeletal bone age radiograph. Which of the following results would allow you to assure him of an excellent prognosis for normal adult height?

146) A 16-year-old girl with an incomplete vaccination record received one dose of the measles, mumps, and rubella (MMR) vaccine during a doctor's visit. One month later, she learns that she is 9 weeks pregnant, and she is concerned about potential birth defects resulting from the MMR vaccine. Which of the following most closely approximates the risk of birth defects secondary to MMR vaccine exposure during the first trimester?

147) A 6-week-old male infant, who was born at 32 weeks' gestation with a birth weight of 1500 g, has had an average weight gain of 8 g/day since birth. He takes an iron-fortified formula that is 24kcal/oz. His calorie intake is about 125kcal/day. It is noted that his stool is poorly formed and bulky. Which of the following dietary modifications will most likely result in decreased steatorrhea and improved weight gain?

148) An 8-year-old sickle-cell patient arrives at the emergency room (ER) in respiratory distress. Over the previous several days, the child has become progressively tired and pale. The child’s hemoglobin concentration in the ER is 3.1 mg/dL. Which of the following viruses commonly causes such a clinical picture?

149) A 7 -year-old boy is rushed to the emergency department after falling on his outstretched hand. He immediately complained of right arm pain after the accident, and he currently cannot move his arm due to the pain. He is crying and holding his right arm in flexion. There is ecchymosis just above his elbow. He cries out in pain when his arm is moved. An x-ray reveals a supracondylar fracture. What secondary injury is most commonly associated with this patient's fracture?

150) A 6-year-old Asian boy is brought by his parents to the office due to high-grade fever and rash for the last 9 days. A brick-red, maculopapular rash first appeared on his face and subsequently spread to his trunk and extremities. Prior to the outbreak of the rash, he had a non-productive cough, tearing of eyes, runny nose, sneezing, and intermittent nasal obstruction. Laboratory findings are as follows: Hct 46%, WBC 2,000/mm3, Platelets 160,000/mm3. Which of the following has been shown to reduce the morbidity and mortality rates of patients with this kind of infection?

152) A 4-month-old infant boy has gained only 10 ounces since birth. He has failed to gain weight with multiple formula preparations. His stools have been loose and fatty. An older sister had similar symptoms and has been repeatedly hospitalized for failure to thrive and recurrent pulmonary infections. Which of the following is the most likely cause of this patient's gastrointestinal symptoms?

153) A term newborn is delivered vaginally following a breech presentation. On physical examination, the Barlow test is positive for bilateral subluxation of the hips. There is decreased abduction of both hips. Besides breech presentation, which of the following infants are most at risk for developmental dysplasia of the hip?

154) A 4-year-old boy, who has a ventriculoperitoneal shunt for congenital hydrocephalus, develops fever, headache, irritability, lethargy, photophobia, and vomiting. His temperature is 39.6 C (103.2 F). He is noted to have nuchal rigidity, with the presence of both Kernig's and Brudzinski's signs. The shunt tract is erythematous on the surface. A lumbar puncture is performed and shows a WBC of 40,000/mm3 with 85% neutrophils, a glucose concentration of 48 mg/dL, and a protein concentration of 169 mg/dL. Which of the following is the most likely pathogen?

155) A 6-month-old male is brought to the office due to fussiness and tugging at his right ear for the past 2 days. He has had a fever of 39.4 C (103 F) for the past 2 days. His past medical history is significant for recurrent ear and lung infections, oral candidiasis, and persistent diarrhea by rotavirus. His temperature is 39.4 C (103F), pulse rate is 150/min, respirations are 28/min, and blood pressure is 80/60mm Hg. Physical examination reveals an erythematous, bulging right tympanic membrane with poor mobility on pneumatic otoscopy. His lymph nodes are not palpable, and his tonsils are not visualized. His B and T lymphocyte levels are markedly reduced. The chest x-ray reveals an absent thymic shadow. What is the most likely etiology of this patient's condition?

156) A 2-year-old child is admitted to your hospital team. The child’s primary care doctor has been following the child for several days and has noted her to have had high fever, peeling skin, abdominal pain, and a bright red throat. You are concerned because two common pediatric problems that could explain this child’s condition have overlapping presenting signs and symptoms. Which of the following statements comparing these two diseases in your differential is true?

157) Two new mothers are discussing their infants outside the neonatal intensive care unit. Both were born at 36 weeks’ gestation. One infant weighs 2600 g (5 lb, 12 oz) while the other infant weighs 1600 g (3 lb, 8 oz). The mother of the second infant should be told that her child is more likely to have which of the following conditions?

158) A 2-day-old male infant is jaundiced. He was born at term from an uncomplicated pregnancy, and was normal at birth. He otherwise appears healthy and is feeding well. Vital signs are stable. Physical examination shows jaundice. There is no organomegaly. Laboratory investigations show: Hemoglobin 17.0 g/L, MCV 88 fl, Platelets 220,000/mm3, Leukocyte count 4,500/mm3, Total bilirubin 7.5 mg/dL, Indirect bilirubin 6.0 mg/dL. What is the most likely cause of this patient's jaundice?

159) An infant in brought to the clinic for a routine healthy visit and vaccinations. She is the product of an uncomplicated pregnancy and has been meeting development mileposts. She is feeding well, and her mother reports that the baby seems to be growing well as well. On physical examination, the infant is afebrile with stable vital signs. She can lift her head to 90 degrees, her eyes follow past the midline, she laughs, regards her own hand and has slight awareness of her mother. Which of the following is the most likely age of this infant?

160) A two-day old infant develops seizures, bulging fontanel, and focal neurologic signs. His temperature is 37 C (98F), pulse is 180/min, and capillary refill is> 2 seconds. The initial work-up reveals a hemoglobin level of 12g/dl. Transfontanel ultrasonography demonstrates a hemorrhage involving the germinal matrix, lateral ventricles, and brain parenchyma. Which of the following is the most significant risk factor for this newborn's condition?

161) A 16-year-old girl, accompanied by her mother, is in your office for a well-adolescent visit. The mother asks about drug and alcohol abuse. You explain that the warning signs of abuse include which of the following?

162) A 3-month-old male infant is brought to the emergency department by his mother because of difficulty in breathing. His mother was admitted in the hospital ten days ago due to a urinary tract infection, and he was cared for by his grandmother during that period. His mother had just been discharged from the hospital yesterday, and noticed that he was constipated and having difficulty with breastfeeding. On examination, he is afebrile. His pulse rate is 110/min, respirations are 36/min with shallow breathing efforts, and blood pressure is 90/50mm Hg. His weight is at the 35th percentile. Examination shows ptosis, dilated pupils with sluggish reaction to light, diminished deep tendon reflexes and decreased muscle tone. What is the most likely mechanism of his illness?

163) A 16-year-old College student presents to the physician's office because of a generalized malaise, sore throat and fever for the past 2 to 3 days. She is given amoxicillin prescription. Twenty-four hours later, she develops a polymorphous rash over her entire body. She has taken amoxicillin in the past for sinus disease and never had any problem. What is the most likely organism that is responsible for her symptoms?

164) 16 An 18-month-old child is brought to the emergency department by his mother due to a one-day history of lethargy and anorexia. He had a fever the whole day yesterday, which responded to Tylenol (Acetaminophen). He then developed a petechial rash over his entire body, which worsened in the last few hours. He is up-to-date with his immunizations, and is an otherwise healthy baby. On examination, he is drowsy and lethargic. He has neck stiffness and appears septic. He flexes his hips when his neck is flexed. What is the most likely organism responsible for the patient's symptoms?

165) A child can walk well holding on to furniture but is slightly wobbly when walking alone. She uses a neat pincer grasp to pick up a pellet, and she can release a cube into a cup after it has been demonstrated to her. She tries to build a tower of two cubes with variable success. She is most likely at which of the following age?

166) A 3-week-old female is brought into the emergency department with a fever and irritability. She was born after a normal pregnancy and delivery. Her mother had routine prenatal care and has no history of sexually transmitted infections. The infant's mother is 14 years old and the father is 17 years old. They are not married, and the father is not involved in the care of the infant. The infant lives with her mother and maternal grandparents at the maternal grandparents' home. You are concerned about meningitis and decide to do a lumbar puncture. The mother and maternal grandparents are present in the emergency department. Informed consent should be obtained from which of the following individuals?

168) A 10-year-old boy is admitted to the hospital because of bleeding. Pertinent laboratory findings include a platelet count of 50,000/μL, prothrombin time (PT) of 15 seconds (control 11.5 seconds), activated partial thromboplastin time (aPTT) of 51 seconds (control 36 seconds), thrombin time (TT) of 13.7 seconds (control 10.5 seconds), and factor VIII level of 14% (normal 38%-178%). Which of the following is the most likely cause of his bleeding?

169) Varicella vaccination is a live virus vaccine. It is generally not recommended in immunocompromised patients. Which of the following is an exception to this rule?

170) The signs and symptoms of meningitis in an infant can be different than those in an adult. Which of the following signs and symptoms of meningitis is more helpful in an adult patient than in a 4-month-old?

171) A woman gives birth to twins at 38 weeks’ gestation. The first twin weighs 2800 g (6 lb, 3 oz) and has a hematocrit of 70%; the second twin weighs 2100 g (4 lb, 10 oz) and has a hematocrit of 40%. Which of the following statements is correct?

172) A 9-month-old African American boy is brought to the office by his parents due to swelling of the feet and hands for the past two days, accompanied by poor feeding and fussiness. His vital signs are stable, except for a temperature of 38.3C (101 F). He appears pale. On examination, the dorsal surface of his hands and feet on both sides are swollen and tender, with restricted range of movement. He is an adopted child, and his family history is not available. Radiography of the feet and hands reveal soft tissue swelling. What is the pathophysiology of this patient's presentation?

173) A 4-year-old child presents in the clinic with an illness notable for swelling in front of and in back of the ear on the affected side, as well as altered taste sensation. Correct statements about this condition include which of the following?

174) A 3-year-old boy is brought to the office by his 27-year-old white mother for the evaluation of recurrent bone fractures. His first fracture was that of the femur, and occured when he was 6 months old. He had a fracture of the wrist 4 months ago. His mother also has a history of multiple fractures since childhood. She lost all her teeth at a very early age and is complaining of deafness. Her husband has a history of severe alcohol abuse. On examination, both mother and son have blue sclerae. What is the most likely involved disease process?

175) A mother brings her infant into the clinic for a routine visit. Examination reveals nothing abnormal. Developmental assessment shows that the infant sits well unsupported, enjoys looking around, babbles, and has a raking grasp. What is the most likely age of this infant?

177) A 6-month-old infant has been exclusively fed a commercially available infant formula. Upon introduction of fruit juices, however, the child develops jaundice, hepatomegaly, vomiting, lethargy, irritability, and seizures. Tests for urine-reducing substances are positive. Which of the following is likely to explain this child’s condition?

178) A term newborn infant from an uncomplicated pregnancy is being examined. He is pink, except for his extremities, which are blue. His heart rate is 150/min, and his respirations are irregular and slow at 40/min. He coughs on nasal stimulation and has some flexion of the extremities. What is his Apgar score?

179) A 2-year-old child is brought to the emergency department because of generalized convulsions that last 15 minutes. He has had a fever for 24 hours, and his current temperature is 39.5 C (103 F). He also has a sore throat, but otherwise looks healthy. His father also had several episodes of febrile seizures in his childhood. Which of the following is the most important factor that will increase the risk of recurrence of febrile seizures?

180) An 8-year-old immigrant from rural Central America presents with complaints of weakness, facial swelling, muscle pain, and fever. A CBC reveals marked eosinophilia. Which of the following parasites is most likely to be responsible?

181) The mother of a 4-year-old child takes her daughter to a pediatrician because she is "scratching all the time." Physical examination demonstrates multiple areas of excoriation, which are worst on the shoulders, buttocks, and abdomen. In the areas where the scratching has occurred, scattered tiny red punctate lesions are also seen. Careful examination of the clothing reveals small, ovoid, grayish-white structures attached to threads on the seams. Which of the following is the most likely causative agent?

182) A previously healthy 6-year-old girl is brought to the office due to a 10-day history of persistent, thick, nasal discharge, nasal congestion, cough, and intermittent low-grade fever. She has had no vomiting, headache, earache, or rash. Her temperature is 37.2 C (98.9 F), blood pressure is 88/50 mmHg, pulse is 90/min, and respirations are 15/min. Physical examination shows clear tympanic membranes, congested posterior nasopharynx with thick, yellow and purulent mucus, and red, swollen nasal turbinates. Transillumination of the sinuses is equivocal. Palpation of the maxillary sinuses shows mild tenderness. Lungs are clearto auscultation. Which of the following organisms is the most common etiologic agent of this condition?

183) A one-month-old infant is brought to the physician for evaluation. His mother reports that for the past two weeks, he has been crying inconsolably for several hours every evening. His mother has tried multiple methods to calm the infant down, but nothing seems to work. The infant was born full term without complications. He takes two ounces of cow's milk-based formula every two hours and is growing well. His mother reports that he is happy and alert the rest of the day. The child's physical examination is unremarkable. Which of the following is a true statement about the child's condition?

184) An 18-month-old male is brought to the hospital because of fever, dyspnea, and productive cough of two days duration. His mother reports that he just recovered from prolonged diarrhea due to Giardia infection. His past medical history is also significant for pneumonia and recurrent ear infections since 6 months of age. On physical examination, his temperature is 38.7°C (101.7°F), pulse is 140/min, and respirations are 40/min. Examination reveals a young child in mild respiratory distress and bronchial breath sounds in the right lower lung lobe. Which of the following is the most likely cause of his recurrent infections?

185) You are called to the nursery to evaluate a newborn infant. The mother is a 24-year-old primigravida. Her pregnancy was complicated by preeclampsia. The infant was delivered at 39-weeks’ gestation via emergent cesarean section due to maternal hypertension and non-reassuring fetal heart tones. On examination, the infant's weight is 2.6 kg (5 lb 11 oz) placing him in the 5th percentile, height is 18 inches (46 em) placing him in the 5th percentile, and head circumference is 13 inches (33 cm) placing him in the 1oth percentile. The infant's head seems large for her body. There is a paucity of subcutaneous fat. The remainder of the physical examination is unremarkable. This infant is at risk for developing which of the following?

186) A 16-year-old girl comes to the physician with headache and vision changes for the past month. The headaches are worse in the morning and are associated with nausea. She takes oral isotretinoin for severe acne. Her temperature is 36.7 C, BP is 130/80 mmHg, Pulse is 70/min, and respirations are 15/min. Eye examination shows papilledema and decreased visual acuity. There is no neck stiffness. Motor examination shows 5/5 strength, 2+ deep-tendon reflexes, and a normal plantar response. Sensory examination is unremarkable. Computed tomography scan of the head is within normal limits. Lumbar puncture shows the following: Opening pressure 280 mm H2O, Cerebrospinal fluid glucose 40 mg/dL, Cerebrospinal fluid protein 40 mg/dL, White blood cell 3/mm3. Which of the following is the most likely cause of this patient’s symptoms?

187) A 3-month-old infant without significant past history was brought to the emergency center by her mother with a generalized tonic-clonic seizure. She is found to have glucose of 5 mg/dL. After correction of her hypoglycemia, she is admitted to your service for further evaluation. Several hours later, her nurse calls to tell you that her bedside glucose check was now 10 mg/dL. You order laboratory work suggested by the pediatric endocrinology team and again correct the infant’s hypoglycemia. The results of the laboratory tests you drew include an elevated serum insulin level of 50 μU/mL, and a low IGFBP-1 (plasma insulin-like growth factor binding protein-1). C-peptide levels are not detectable. Which of the following is the likely cause of this child’s recurrent hypoglycemia?

188) A 10-year-old African American boy is brought to the office for the evaluation of worsening fatigue for the past few weeks. He has sickle cell anemia, and has had several hospitalizations for painful crises. His vital signs are stable. He appears pale. He has a hemoglobin level of 7. 7 g/dl and hematocrit of 22.5%. Which is the most likely type of anemia of this patient?

189) A 6-year-old child has had repeated episodes of otitis media. She undergoes an uneventful surgical placement of pressure-equalization (PE) tubes. In the recovery room she develops a fever of 40C (104F), rigidity of her muscles, and metabolic and respiratory acidosis. Which of the following is the most likely explanation for her condition?

190) A 3-year-old-boy ingests 40 of his older sister's chewable vitamin tablets, as well as 3 tablets of 250 mg of acetaminophen. The ingredients in the multivitamin tablets are as follows: Vitamin A 3000 IU, Thiamine 1 mg, Vitamin C 75 mg, Vitamin B6 1 mg, Vitamin D 400 IU, Iron 12 mg, Fluoride 1 mg. The child is brought to the emergency department in no acute distress. Which of the following complications may occur if appropriate therapy is not undertaken?

191) A 7-year-old boy presents with tenderness and erythema of one knee joint. He has had troubles with infections since about 3 months of age. A brother and a maternal uncle both died of infectious disease at an early age. A detailed immunologic evaluation performed at 2 years of age demonstrated plasma IgG less than 50 mg/100 mL. Normal numbers of circulating T cells and normal cellular immunity were found. The boy had been treated monthly since then with IV immunoglobulin. This therapy had markedly reduced, but not eliminated, the boy's infection rate. Which of the following is the most likely pathogen to cause infectious arthritis in this patient?

192) A 3-week-old African American boy is brought to the Emergency Department because of a generalized seizure 2 hours ago. The infant is highly irritable with incessant high pitched crying. The infant's weight is 2.5 kg (250 gm below birth weight), blood pressure is 70 /40 mm Hg, pulse is 145/min and respirations are 50/min. Laboratory results show: Blood glucose 120 mg/dL, Urea nitrogen 50 mg/dL, Serum sodium 170 mEq/L, Serum calcium 8.5 mg/dL, Serum magnesium 1.5 mg/dL. Which of the following is the most likely cause of this infant’s seizure?

193) A neonate born at term is found to have webbed neck and swollen hands and feet. Ultrasonogram of the abdomen shows a horseshoe kidney. Which of the following is the most likely cause of edema?

194) An 8-year-old girl is being evaluated for short stature. She is at 8th percentile for height and 30th percentile for weight. Vital signs are within normal limits. Examination shows a high arched palate and inverted, widely spaced nipples Karyotyping shows 45 XO. Which of the following is she most at risk of developing?

195) A premature infant has a difficult delivery with episodes of arrhythmia and suspected hypoxiaischemia. After the delivery, the infant is lethargic and has periods of apnea. Intracranial hemorrhage is suspected. No obvious head trauma is noted. Cranial ultrasound identifies blood within the ventricles. Which of the following structures is the most likely source of the hemorrhage?

196) A 16-year-old girl is in your office for a preparticipation sports examination. She plans to play soccer in the fall, and needs her form filled out. Which of the following history or physical examination findings is usually considered a contraindication to playing contact sports?

197) A 15-year-old boy is in the office for a preparticipation sports physical examination before he begins playing with the varsity football team at his school. Although he is a skilled receiver, he will be one of the smallest players on the field and is concerned about the potential for injury. He asks how to bulk up. Appropriate advice to increase muscle mass includes which of the following?

198) A 3-week-old boy presents to the physician's office with a 1-week history of forceful, projectile vomiting. He has been vomiting after almost every feeding. The vomitus contains mostly undigested formula and is non-bilious. On examination, his oral mucosa is dry, his anterior fontanel appears to be depressed, and his capillary refill is 3-4 seconds. An abdominal examination reveals an olive-sized mass in the epigastrium. Which of the following electrolyte findings will most likely be seen?

199) A 3-month-old infant is taken to the emergency department with constipation and behavioral changes. Physical examination demonstrates ptosis and an absence of facial expression. The child appears conscious but has trouble following a toy with her gaze. The crying is very weak, and saliva is pooling in her mouth. She is also developing a generalized hypotonia, and breathing is becoming more shallow. This child's condition is most likely related to ingestion of which of the following food products?

200) A blood type B infant born to a blood type O mother has clinically significant fetal-maternal blood group incompatibility with mild anemia and a weakly positive Coombs test. The infant develops jaundice a few hours after birth, with a bilirubin (measured at 12 hours after birth) of 12 mg/dL (predominately unconjugated) compared with 3.5 mg/dL in cord blood. The physician is concerned that the rising bilirubin levels will damage the infant's nervous system. Which of the following sites is most vulnerable to this injury?

201) A 15-year-old girl is brought to the pediatrician's office because of sudden deterioration of school performance. Over the past month, her mother has noticed an occasional paint stain on the girl's hands. Her mother also noticed six bottles of typewriter correction fluid in her bedroom about a week ago. She raised the concern of inhalant abuse. Which of the following is the most likely consequence of chronic inhalant abuse?

202) A 4-year-old child comes in for a health maintenance visit. His mother is concerned that he is not doing some things that other kids in his preschool do. Which of the following skills would be expected of a 4-year-old?

203) A mother brings her 3-year-old son to the pediatrician because he has had 7 days of fever and a painful swollen lymph node in his right groin. This is the boy's sixth episode of lymph node swelling; previous episodes resolved after drainage and prolonged antibiotic therapy. The child also has a past medical history significant for pneumonia at 12 months of age that required chest tube placement for drainage. His maternal uncle died in childhood from recurrent infections. On examination, the boy is at the 5th percentile for both height and weight His temperature is 38.5 c (101.3 F). There is an enlarged, tender lymph node in the right inguinal area with erythema and warmth of the overlying skin. There are several healed incisions in the inguinal regions bilaterally, as well as around the neck from old drainage sites. Laboratory analyses reveal the following: Hematocrit 35%, Platelet count 350,000/mm3, Leukocyte count 17000/mm3, Segmented neutrophils 65%, Bands 10%, Lymphocytes 25%. Gram stain of fluid aspirated from the affected lymph node reveals numerous bacteria-filled segmented neutrophils. Cultures grow S. aureus. What is the most likely mechanism underlying these findings?

204) A 7-year-old boy has cramping abdominal pain and a rash mainly on the back of his legs and buttocks as well as on the extensor surfaces of his forearms. Laboratory analysis reveals proteinuria and microhematuria. You diagnose Henoch-Schönlein, or anaphylactoid, purpura. In addition to his rash and abdominal pain, what other finding is he likely to have?

205) An infant is brought to a hospital because her wet diapers turn black when they are exposed to air. Physical examination is normal. Urine is positive both for reducing substance and when tested with ferric chloride. This disorder is caused by a deficiency of which of the following?

207) A 23-year-old primigravida comes to the physician for a prenatal visit. She is considering breastfeeding her infant, and the physician discusses the benefits of breastfeeding for both the mother and the infant. She asks if there are any reasons that she should not breastfeed. Which of the following maternal conditions is a contraindication to breastfeeding?

208) A 1-year-old patient is in the office for a health maintenance visit and is ready for immunizations. The child has a mild upper respiratory infection and a low-grade fever. The mother does not want the child to receive vaccine because she has been told that the vaccine could make the illness worse. You tell her the only true contraindication to vaccination is which of the following?

209) An infant comes to the office for his 1-year check-up. His father states that he is worried that his son is smaller than he should be. The child's weight is 8.6 kg (19 lb), and his length is 71 cm (28 in). He appears to be growing appropriately on his growth curve. Which of the following is the most appropriate explanation about growth to be given to the father?

210) A 15-year-old Ashkenazi Jewish boy comes to the office because of pain in his right knee. He gives a history of easy bruising and chronic fatigue. His height and weight are in the 40th percentile mark for his age. The physical examination reveals tenderness over the lower end of the right femur, mildly enlarged liver, and moderately enlarged spleen. X-rays of the right femur reveal an Erlenmeyer flask deformity of the distal femur. Significant lab findings are anemia and thrombocytopenia. A bone marrow examination reveals cells with a wrinkled paper appearance. What is the most likely cause of this patient's condition?

211) A 7-year-old girl is brought to the office by her mother. The mother is worried because she noticed some axillary hair development in her daughter. The girl appears calm, and denies the presence of headaches, visual disturbances or abdominal pain. There has been no change in her behavior. Her medical history is unremarkable. Her older sister's pubertal changes began at age 11. Physical examination reveals scarce and dark axillary hair, absent breast development and absent pubic hair. The rest of the examination is unremarkable. Activation of which of the following structures is most likely responsible for this patient's symptomatology?

212) An 8-year-old boy is seen in the pediatrician's office for a routine health supervision visit. The mother states that he has Duchenne muscular dystrophy. On examination, he is found to have hip waddle and enlargement of both calves. He is ambulatory, but his muscle strength is diminished symmetrically. Which of the following signs is most consistent with Duchenne muscular dystrophy?