A biologically active 20-alpha-reduced metabolite of PROGESTERONE. It is converted from progesterone to 20-alpha-hydroxypregn-4-en-3-one by the 20-ALPHA-HYDROXYSTEROID DEHYDROGENASE in the CORPUS LUTEUM and the PLACENTA.

Synonyms: 20-alpha-hydroxy- Pregn-4-en-3-one, Pregn 4 en 3 one, 20 alpha hydroxy, 20-alpha-Dihydroprogesterone, 20 alpha Hydroxyprogesterone, Dihydroprogesterone, 20alpha Hydroxypregn 4 Ene 3 One, 20alpha-Hydroxypregn-4-Ene-3-One, 20 alpha Dihydroprogesterone, Pregn-4-en-3-one, 20-alpha-hydroxy-, 20 alpha Hydroxy 4 Pregnen 3 One, Pregn-4-en-3-one, 20-hydroxy-, (20S)-, 20 alpha-Dihydroprogesterone, 20 alpha-Hydroxyprogesterone, 20 alpha-Hydroxy-4-Pregnen-3-One, 145-14-2, 20-alpha-Hydroxyprogesterone