Chapter·BiochemistryLipid metabolism

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1

A 6-day-old infant who was born via uncomplicated vaginal delivery at 39 weeks of gestation is brought to the family physician for poor feeding. The mother received adequate prenatal care throughout the pregnancy, and has no medical conditions. On physical exam, the infant's temperature is 36.5°C (97.7°F), blood pressure is 70/45 mmHg, pulse is 170/min, and respirations are 40/min. The infant has dry mucous membranes, capillary refill of 4 seconds, and a depressed anterior fontanelle. No abdominal masses are noted. Genital exam shows enlargement of the clitoris with fusion of the labioscrotal folds. Serum chemistry is remarkable for hyponatremia and hyperkalemia. The infant's karyotype is 46,XX. Which of the following findings are most likely to be discovered upon further workup?

AIncreased aldosterone, decreased cortisol

BDecreased aldosterone, increased 11-deoxycorticosterone

CIncreased sex hormones, decreased renin activity

DIncreased sex hormones, increased 17-hydroxyprogesterone

EDecreased cortisol, decreased sex hormones

2

A 6-year-old boy is brought to the physician by his mother who is concerned about his early sexual development. He has no history of serious illness and takes no medications. He is at the 99th percentile for height and 70th percentile for weight. His blood pressure is 115/78 mm Hg. Examination shows greasy facial skin and cystic acne on his forehead and back. There is coarse axillary and pubic hair. Serum studies show: Cortisol (0800 h) 4 μg/dL Deoxycorticosterone 2.5 ng/dL (N = 3.5–11.5) Dehydroepiandrosterone sulfate 468 mcg/dL (N = 29–412) Which of the following is the most likely underlying cause of this patient's symptoms?

ADeficiency of 21β-hydroxylase

BIdiopathic overproduction of GnRH

CConstitutive activation of adenylyl cyclase

DDeficiency of 11β-hydroxylase

EDeficiency of 17α-hydroxylase

3

A newborn female is found to have ambiguous genitalia and hypotension. Laboratory workup reveals hyperkalemia, hyperreninemia, and elevated levels of 17-hydroxyprogesterone in the patient's urine. Which of the following enzymes would you expect to be deficient in this patient?

A11-hydroxylase

B3β-hydroxysteroid dehydrogenase

C11β-hydroxysteroid dehydrogenase

D21-hydroxylase

E17-hydroxylase

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