582 Obstetrics and Gynecology Board Review •••
❍ What are the different clinical presentations/syndromes of 21-hydroxylase deficiency?
(1) Classical form: Simple virilizing form (genital ambiguity—female infants have pseudohermaphroditism; males
have normal sexual development)/salt-wasting form (two-third of infants), may cause sexual precocity in
children—if not virilized at birth and disorder is overlooked.
(2) Nonclassical form/late-onset form: During childhood or early adolescence, they may present with precocious
puberty. Symptoms at time of puberty or soon thereafter include acne, hirsutism, menstrual irregularity, and
infertility issues.
❍ What percentage of hirsute patients may have 21-hydroxylase enzyme deficiency?
5%.
❍ The genetic inheritance pattern of CAH due to 21-hydroxylase deficiency is?
Autosomal recessive. It is the most common autosomal-recessive disorder (more common than sickle cell and cystic
fibrosis).
❍ What percentage of Caucasian hyperandrogenic women have late-onset CAH?
1% to 2%.
❍ The complete form of 21-hydroxylase enzyme deficiency results in a lack of what two important
glucocorticoid and mineralocorticoid steroids?
Cortisol and aldosterone.
❍ How do you screen for 21-hydroxylase deficiency for late-onset form?
Obtain 8 am follicular phase 17-hydroxyprogesterone level. It should be <200 ng/dL. If >800, nonclassical CAH
is diagnosed. If it is 200 to 800 ng/dL, then an ACTH stimulation test should be performed—synthetic ACTH
(cosyntropin) is given and in most affected patients 17OHP levels rise to above 1500 ng/dL (43 nmol/L); if
borderline results, genotyping should be done.
❍ What is the treatment of CAH?
A glucocorticoid and usually a mineralocorticoid.
❍ Other rare enzyme deficiencies that result in hirsutism include?
3 b-hydroxysteroid dehydrogenase (3b-HSD) and 11b-hydroxylase deficiency.
❍ How can a 3b-HSD enzyme defect be diagnosed?
By performing an ACTH stimulation test and finding an elevated 17-hydroxypregnenolone to
17 hydroxyprogesterone ratio (usually >6.0). You will also see an increase in DHEA-S levels. There
is now gene sequence testing available as well.
❍ How do you diagnose an 11b-hydroxylase enzyme deficiency?
Presence of hypertension and an elevated serum 11-deoxycorticosterone.
❍ Between what gestational weeks does exposure to androgen excess result in female sexual ambiguity?
Between gestation weeks 7 and 12.