Abstract
Plasma 17-hydroxyprogesterone (17-OHP) concentrations in normal men averaged 0.094 mug/100 ml. Studies using suppressive doses of androgens and glucocorticoids showed that 90% of the 17-OHP originated from the Leydig cell. The 17-OHP production rate was 1.8 mg/24 hr. Plasma 17-OHP has a marked circadian variation, the 8 p.m. values being only 40% of the 8 a.m. values. Plasma luteinizing hormone measured in the same samples did not vary. The adrenal cortex has the capacity to synthesize and secrete 17-OHP and progesterone since adrenocorticotrophic hormone (ACTH) caused a fourfold increase in these plasma steroids. In children with congenital adrenal hyperplasia, plasma 17-OHP levels were 50-200 times those of normal men and plasma progesterone was increased 6- to 10-fold over normal men.