576 Obstetrics and Gynecology Board Review •••
❍ What are the effects of excess androgen in pubertal girls?
Virilization, primary or secondary amenorrhea, and increased skeletal maturation.
❍ What are the effects of excess androgen in adult males?
Inhibits gonadotropin secretion that may lead to decreased testes size, testicular testosterone secretion, and
spermatogenesis.
❍ What are the effects of excess androgen in adult females?
Hirsutism, acne, male pattern baldness, menstrual irregularities, oligomenorrhea or amenorrhea, and infertility.
❍ Define clitoromegaly.
Clitoral length >10 mm or a clitoral index (length times width) >35 mm.
❍ Which of the following increase SHBG (the others decrease it)? (1) Estrogens, (2) danazol, (3) OCPs,
(4) androgens, (5) liver disease, (6) pregnancy, and (7) hyperthyroidism.
1, 3, 6, 7.
❍ Low levels of sex hormone binding globulin (SHBG) during pregnancy have been associated with the risk of
developing what pregnancy complication?
Gestational diabetes.
❍ How does danazol treatment (in endometriosis) result in hyperandrogenism?
Danazol (an isoxazol derivative of 17a-ethinyltestosterone) decreases SHBG production and therefore elevates free
testosterone levels. It also cross reacts with the androgen receptor.
❍ What happens to SHBG concentration in hyperandrogenic women with PCOS and how does it affect total
and free testosterone?
Low SHBG levels result in normal to slightly increased total testosterone and increased free testosterone.
❍ What percentage of testosterone is unbound or free in the circulation in normal females, hirsute females,
and males?
1%, 2%, and 3%.
❍ What percentage of circulating testosterone is bound to SHBG in normal females, hirsute females, and males?
80%, 79%, and 78%.
❍ What percentage of circulating testosterone is bound loosely to albumin?
19%.
❍ What is the immediate precursor to testosterone and what is the enzyme, present in most tissues, that aids
its conversion to testosterone?
Androstenedione, which is converted by 17b-hydroxysteroid dehydrogenase (17-ketosteroid reductase) to
testosterone.