Congenital Adrenal Hyperplasia
Also written as CAH.
Adrenogenital Syndromes (Congenital Adrenal Hyperplasia — CAH)
What our notes say
- Adrenogenital Syndromes (Congenital Adrenal Hyperplasia — CAH) (ENDOCRINE PATHOLOGY)
- Congenital Adrenal Hyperplasia: Enzyme defects → androgen excess. (Endocrine LAqs and SAqs)
- Congenital adrenal hyperplasia (CAH) – enzyme defects, hormone imbalance (Endocrine LAqs and SAqs)
- 21-hydroxylase deficiency: The most common cause of Congenital Adrenal Hyperplasia (CAH), leading to impaired cortisol and aldosterone synthesis, and shunting of precursors towards androgen production. (Steroid and Sex Hormones)
Study material on Congenital Adrenal Hyperplasia
- Chemical pathology and Endocrine pathology
- Chemical Pathology Practice Examination
- Endocrine LAqs and SAqs
- Steroid and Sex Hormones
- Year 3: Endocrine and Metabolic Pathology
Practice questions on Congenital Adrenal Hyperplasia
Which enzyme deficiency is most common in congenital adrenal hyperplasia?
- 21-hydroxylase
- 17-hydroxylase
- 11β-hydroxylase
- 5α-reductase Correct
Answer: A. 21-hydroxylase deficiency accounts for ~95% of CAH cases, leading to cortisol deficiency and androgen excess. ## Section 3: Kidney Function & Electrolytes ---
21-hydroxylase deficiency, the MOST common cause of congenital adrenal hyperplasia, leads to
- Deficient cortisol and aldosterone, excess androgens
- Deficient cortisol and androgens, excess aldosterone
- Deficient aldosterone and androgens, excess cortisol
- Excess cortisol, aldosterone, and androgens
Answer: A. 21-hydroxylase deficiency blocks cortisol and aldosterone synthesis. The shunted pathway results in excess androgens, causing virilisation in females (ambiguous genitalia) and precocious puberty in males. Salt-wasting (aldosterone deficiency) is common. ---
In 21-hydroxylase deficiency (congenital adrenal hyperplasia), which metabolite is diagnostically elevated?
- Cortisol
- Aldosterone
- 17-hydroxyprogesterone
- DHEA-S
Answer: C. 17-OHP accumulates proximal to the enzymatic block; markedly elevated in classic CAH. ---
The most common cause of congenital adrenal hyperplasia (CAH) is
- 11β-hydroxylase deficiency
- 17α-hydroxylase deficiency
- 3β-HSD deficiency
- 21-hydroxylase deficiency
Answer: D. ~95% of CAH. Blocks cortisol and aldosterone synthesis → precursors shunted to androgens. Elevated 17-hydroxyprogesterone is the diagnostic marker. ---
In congenital adrenal hyperplasia due to 21-hydroxylase deficiency, which metabolite is elevated? ---
- Cortisol
- Aldosterone
- 17-hydroxyprogesterone
- DHEA only
Answer: C.