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Difficulty: HardPediatric Endocrine Disorders

Match each pediatric clinical presentation to its most likely underlying enzymatic deficiency.

  • A 2-week-old 46,XX infant presents with clitoromegaly, partial labial fusion, serum sodium of 122 mEq/L, and serum potassium of 6.5 mEq/L.21-hydroxylase deficiency
  • A 2-week-old 46,XX infant presents with ambiguous genitalia, a blood pressure >95th percentile for age, and a serum potassium of 2.8 mEq/L.11β-hydroxylase deficiency
  • A 15-year-old phenotypic female presents with primary amenorrhea, absent secondary sexual characteristics, a blood pressure of 145/95 mmHg, and a 46,XY karyotype.17α-hydroxylase deficiency
  • A 2-week-old 46,XX infant presents with ambiguous genitalia, normal blood pressure, and normal electrolytes, accompanied by a maternal history of severe facial hair growth and voice deepening during the pregnancy.Placental aromatase deficiency

Answer

The correct matches correlate 21-hydroxylase deficiency with salt-wasting CAH, 11β-hydroxylase deficiency with hypertensive virilizing CAH, 17α-hydroxylase deficiency with hypertensive sexual infantilism, and placental aromatase deficiency with virilization alongside normal electrolytes.
Each disorder presents with a unique constellation of mineralocorticoid, glucocorticoid, and sex hormone derangements depending on the specific location of the enzymatic block in the steroidogenesis pathway.

Step-by-Step Solution

1
Evaluate the electrolyte and blood pressure profile to determine the presence of mineralocorticoid excess or deficiency.
Hyponatremia and hyperkalemia indicate mineralocorticoid deficiency. Hypertension and hypokalemia indicate mineralocorticoid excess.
This establishes whether the block in the steroidogenesis pathway occurs before or after the synthesis of mineralocorticoid precursors.
2
Assess the phenotypic sex and karyotype against the degree of virilization.
Virilized 46,XX infants have excess androgens, whereas a 46,XY patient appearing as a phenotypic female has deficient androgens.
This identifies if the enzymatic block prevents sex hormone synthesis (as in 17α-hydroxylase deficiency) or shunts precursors toward it (as in 21- and 11β-hydroxylase deficiencies).
3
Incorporate maternal history for isolated virilization cases with normal adrenal function.
Maternal virilization combined with a virilized 46,XX infant points to a placental block rather than an adrenal defect.
Aromatase is required in the placenta to clear fetal androgens by converting them to estrogens; without it, androgens accumulate and virilize both the fetus and the mother.

Key Concept

Steroidogenesis pathway enzyme deficiencies and their corresponding clinical presentations
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Topics

Pediatric Endocrine Disorders

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