17-Hydroxyprogesterone

The 17-Hydroxyprogesterone test (also known as 17-OH progesterone or 17-OHP) is used in newborn screening and diagnostic workup of congenital adrenal hyperplasia, most commonly due to CYP21A2 mutations leading to 21-hydroxylase deficiency. It supports confirmation when clinical findings point to adrenal insufficiency or a salt-wasting crisis. In older children and adults, 17-hydroxyprogesterone measurement assists in diagnosing nonclassic (late-onset) congenital adrenal hyperplasia and in monitoring glucocorticoid therapy in established 21-hydroxylase deficiency. The test helps exclude congenital adrenal hyperplasia in patients evaluated for hyperandrogenism, hirsutism, or menstrual disturbance, and may aid assessment of infertility and, less commonly, suspected adrenal or ovarian tumors.

17-Hydroxyprogesterone is an intermediate in cortisol synthesis, and adrenal production is driven by pituitary ACTH. When enzymes required for cortisol biosynthesis—most often 21-hydroxylase—are deficient, 17-hydroxyprogesterone accumulates and adrenal androgen secretion increases. This biochemical pattern underlies the spectrum of congenital adrenal hyperplasia, encompassing classic salt-wasting and simple virilizing forms, as well as nonclassic disease. In classic disease, affected females may present at birth with ambiguous genitalia, whereas males typically appear normal neonatally and later develop premature virilization. Nonclassic congenital adrenal hyperplasia presents later with variable hyperandrogenic signs and menstrual dysfunction. About three quarters of classic cases have impaired aldosterone synthesis with salt wasting, which in newborns may manifest as hyponatremia, hyperkalemia, elevated plasma renin activity, and life-threatening dehydration.