Which enzymes are typically checked to diagnose congenital adrenal hyperplasia?

Congenital adrenal hyperplasia (CAH) primarily results from a deficiency in enzymes involved in steroid biosynthesis within the adrenal glands. The most common form of CAH, which accounts for approximately 90% of cases, is due to a deficiency of the 21-hydroxylase enzyme. This enzyme plays a crucial role in the conversion of progesterone to 17-hydroxyprogesterone and of 17-hydroxyprogesterone to 11-deoxycortisol. This deficiency leads to reduced production of cortisol and aldosterone, typically causing an accumulation of steroid precursors, such as 17-hydroxyprogesterone.

Checking the levels of 21-hydroxylase specifically targets this critical deficiency and helps diagnose the most common form of CAH. In addition to 21-hydroxylase, testing for 17-hydroxylase and 11-hydroxylase can be relevant as they may be associated with other forms of adrenal enzyme disorders. Thus, analyzing these three particular enzymes provides a comprehensive approach to diagnosing congenital adrenal hyperplasia and understanding the patient's metabolic profile.

While other choices list different combinations of hydroxylases, they do not focus appropriately on the crucial enzyme deficiency that