Elevated 11-deoxycorticosterone (11-DOC) is characteristic of deficiency of which enzyme in congenital adrenal hyperplasia?

• A. 11β-hydroxylase
• B. 21-hydroxylase
• C. 17α-hydroxylase
• D. 3β-hydroxysteroid dehydrogenase

Answer: (A)

When a specific step in adrenal steroid synthesis is blocked, the substrates upstream of that block accumulate in a characteristic pattern. Here, 11β-hydroxylase normally converts 11-deoxycorticosterone to corticosterone and 11-deoxycortisol to cortisol. If this enzyme is deficient, 11-deoxycorticosterone builds up. Since 11-DOC acts like a mineralocorticoid, its elevation leads to hypertension and low-renin states, which is a classic clue pointing to 11β-hydroxylase deficiency. Other enzyme blocks produce different steroid profiles and clinical signs (for example, 21-hydroxylase deficiency causes androgen excess and salt-wasting, not just elevated 11-DOC). Therefore, elevated 11-deoxycorticosterone best indicates a deficiency of 11β-hydroxylase.