Sex hormones
Progesterone
Luteal-phase steroid; ovulation confirmation and pregnancy support.
Sample
Serum
Clinical reference range
5 to 20 ng/mL
Mid-luteal · Follicular <1; postmenopausal <0.5
Conv: 5–20 ng/mL
Biology
What it measures
Synthesized by corpus luteum and (after ~10 wk) placenta. Stabilizes endometrium.
Clinical use
Why we order it
Day-21 (mid-luteal) progesterone >3 ng/mL confirms ovulation.