Salt-wasting CAH vs Hypertensive CAH
How to tell Salt-wasting CAH and Hypertensive CAH apart when a board question makes them look alike.
21 has salt wasting and virilization; 11 has hypertension and virilization; 17 has hypertension with low androgens/sexual infantilism.
Side by side
21-hydroxylase deficiency causes low cortisol, low aldosterone, high androgens, salt wasting, hypotension, hyperkalemia, and virilization.
11-hydroxylase deficiency causes low cortisol, high androgens, hypertension from deoxycorticosterone; 17-hydroxylase deficiency causes low cortisol/androgens with hypertension and sexual infantilism or undervirilization.
Blocked 21-hydroxylase prevents cortisol and aldosterone synthesis, shunting precursors into androgen production.
Blocked 11-hydroxylase builds mineralocorticoid-active deoxycorticosterone and androgens; blocked 17-hydroxylase builds mineralocorticoids but reduces sex steroid production.
High 17-hydroxyprogesterone, hyponatremia, hyperkalemia, hypotension, and virilization support 21-hydroxylase deficiency.
Hypertension with virilization supports 11-hydroxylase deficiency; hypertension with low sex steroids and delayed puberty supports 17-hydroxylase deficiency.
The trap
All lower cortisol and raise ACTH, so blood pressure, potassium, and androgen phenotype separate them.
The repair move
For congenital adrenal hyperplasia, walk the three enzyme deficiencies in order: (1) 21-hydroxylase deficiency (most common, 90 percent of CAH) is SALT-WASTING virilization: low cortisol, low aldosterone (so HYPOTENSION, HYPONATREMIA, HYPERKALEMIA, metabolic acidosis), high ACTH driving androgen overproduction (virilization, ambiguous genitalia in females, precocious puberty in males); presents with neonatal crisis. (2) 11-beta-hydroxylase deficiency is HYPERTENSIVE virilization: low cortisol, low aldosterone but high 11-deoxycorticosterone (a weak mineralocorticoid causing HYPERTENSION and HYPOKALEMIA), high androgens (virilization). (3) 17-alpha-hydroxylase deficiency is HYPERTENSIVE with LOW androgens: low cortisol, high mineralocorticoids (HYPERTENSION, HYPOKALEMIA), LOW sex hormones (ambiguous genitalia in males with undescended testes, sexual infantilism in females, primary amenorrhea). All three deficiencies are treated with glucocorticoid replacement (hydrocortisone) plus mineralocorticoid (fludrocortisone) only in the salt-wasting form.
Try a free question
CoreA newborn has ambiguous genitalia, vomiting, dehydration, hypotension, hyponatremia, hyperkalemia, and elevated 17-hydroxyprogesterone. Which enzyme deficiency is most likely?
Show answer and explanation
Answer: A. 21-hydroxylase deficiency. Salt wasting with virilization and elevated 17-hydroxyprogesterone points to 21-hydroxylase deficiency.
Why the other choices are tempting
- B. 11-hydroxylase deficiency causes hypertension with virilization.
- C. 17-hydroxylase deficiency causes hypertension with low sex steroid production.
- D. Aromatase deficiency affects estrogen synthesis but does not cause classic salt-wasting CAH.
- E. 5-alpha-reductase deficiency affects DHT production and undervirilization, not cortisol/aldosterone synthesis.
Flashcards
Tap a card to flip it.
What CAH pattern points to 21-hydroxylase deficiency?
Salt wasting, hypotension, hyperkalemia, and virilization point to 21-hydroxylase deficiency.
What CAH pattern points to 11-hydroxylase deficiency?
Hypertension with virilization points to 11-hydroxylase deficiency.
Quick answers
What is the fastest way to tell Salt-wasting CAH from Hypertensive CAH?
21 has salt wasting and virilization; 11 has hypertension and virilization; 17 has hypertension with low androgens/sexual infantilism.
What is the key clue for Salt-wasting CAH?
21-hydroxylase deficiency causes low cortisol, low aldosterone, high androgens, salt wasting, hypotension, hyperkalemia, and virilization.
What is the key clue for Hypertensive CAH?
11-hydroxylase deficiency causes low cortisol, high androgens, hypertension from deoxycorticosterone; 17-hydroxylase deficiency causes low cortisol/androgens with hypertension and sexual infantilism or undervirilization.
What is the common trap with Salt-wasting CAH vs Hypertensive CAH?
All lower cortisol and raise ACTH, so blood pressure, potassium, and androgen phenotype separate them.