he Serum 17-Hydroxy-Pregnenolone test measures steroid level required for adrenal biosynthetic pathway. This test is crucial for the diagnosis of congenital adrenal hyperplasia (CAH) resulting from 21-hydroxylase deficiency. 17-OH-progesterone serves as a substrate for 21-hydroxylase and acts as a disease-specific diagnostic marker for 21-OH deficiency. Healthcare professionals use this test to assess adrenal function and identify potential enzymatic defects.