Mid leuteal progesterone peak?

Reading File

Finding Sources

Reading File

Here is a clear, textbook-sourced summary of the mid-luteal progesterone peak:

Mid-Luteal Progesterone Peak

Timing

Occurs on days 21-23 of a standard 28-day cycle, which corresponds to 7 days after the LH surge (i.e., LH+7).
This is the point of peak progesterone secretion by the corpus luteum and the optimal time to sample serum progesterone for ovulation confirmation.

Normal Peak Values

Source	Peak Value
Ganong's Medical Physiology	~18 ng/mL (60 nmol/L)
Berek & Novak's Gynecology	Typically well above 3 ng/mL (10 nmol/L) when ovulatory
Swanson's Family Medicine	>5 ng/mL (>19 nmol/L) = presumptive evidence of ovulation

So the physiological peak sits around 18 ng/mL / 60 nmol/L, with levels >10 ng/mL being strongly confirmatory and even levels >3 ng/mL (10 nmol/L) being the lower cutoff for confirming ovulation in most labs.

Clinical Use (Confirming Ovulation)

A level >3 ng/mL (>10 nmol/L) is the minimum threshold used to confirm ovulation in most laboratories.
A level >10 ng/mL (>30 nmol/L) is the more commonly cited clinical threshold for confirming an adequate luteal phase.
A level >5 ng/mL (>19 nmol/L) is described as "presumptive evidence" of ovulation in family medicine practice.

Important Caveats

Progesterone is secreted in pulses during the luteal phase, so a single measurement can vary significantly even within a 60-90 minute window. A low isolated result does not definitively diagnose anovulation.
In irregular cycles, sampling on "day 21" is unreliable - the sample should instead be taken 7 days before the expected next period, or guided by LH kit detection.
Follicular phase baseline: ~0.9 ng/mL (3 nmol/L) in women; corpus luteum then drives levels up ~20-fold to the mid-luteal peak.

Sources: Ganong's Review of Medical Physiology (26th ed.); Berek & Novak's Gynecology; Swanson's Family Medicine Review.

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