Clinical Scenario:
A 7-year-old boy is evaluated for rapid linear growth, deepening of the voice and progressive enlargement of the penis over the past 2 years. His height is above the 97th percentile and bone age is 11 years. Blood pressure is 150/95 mmHg on repeated measurements. Serum potassium is mildly reduced and plasma renin activity is suppressed. Serum testosterone is elevated, while cortisol is low-normal.
Which of the following enzyme deficiencies best explains this presentation?
A. 11β-hydroxylase deficiency
B. 17α-hydroxylase deficiency
C. 21-hydroxylase deficiency
D. 5α-reductase deficiency
E. 3β-hydroxysteroid dehydrogenase deficiency
Correct answer & Explanation:
Answer: A. 11β-hydroxylase deficiency
Why this is better for postgraduate exams:
The candidate has to recognize the combination:
Androgen excess → precocious/virilizing puberty
Hypertension + suppressed renin → mineralocorticoid effect
→ 11β-hydroxylase deficiency
In 11β-hydroxylase deficiency, DOC accumulates and has mineralocorticoid activity, producing hypertension and renin suppression, while increased adrenal androgen production causes virilization and precocious pubertal development.
The key differential they are testing
- 21-hydroxylase: androgen excess + salt wasting/hypotension
- 11β-hydroxylase: androgen excess + hypertension
- 17α-hydroxylase: hypertension + low sex steroids/undervirilization
