What does the Progesterone test measure?

Why is Progesterone measured?

Mid-luteal serum progesterone (typically drawn on day 19–22 of a 28-day cycle, or 7 days before anticipated menstruation) is the standard biochemical confirmation of ovulation. Luteal phase progesterone below 3–5 ng/mL suggests anovulation or inadequate corpus luteum function. In perimenopause, declining progesterone precedes oestrogen decline and is associated with sleep disturbance, anxiety, and menstrual irregularity. Bioidentical progesterone therapy monitoring requires careful timing relative to the dosing protocol.

Reference ranges

Standard reference

Follicular phase: 0.1–0.8 ng/mL; Luteal phase: 1.7–27.0 ng/mL; Postmenopausal: <0.1 ng/mL # REVIEWER FLAG: Confirm Access Medical Laboratories phase-specific reference ranges. Luteal phase ranges vary significantly between laboratories — some extend to 27 ng/mL, others to 20 ng/mL. Cycle day of collection is essential context.

Functional medicine optimal

Mid-luteal: >10 ng/mL to confirm adequate ovulation; functional medicine integrative protocols typically target 15–25 ng/mL mid-luteal. # REVIEWER FLAG: Optimal luteal progesterone thresholds vary between guidelines and integrative protocols — reviewer to confirm.

Units

ng/mg creatinine, ng/mL, nmol/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.