So your progesterone levels seem to be all over the place… what gives!⁣?

I get this question in my inbox a few times a month, so let’s try to figure out what’s going on!

Progesterone is secreted in pulses. This “pump” system produces spikes of progesterone throughout the day. ⁣That means progesterone fluctuates a LOT!

In just a 90-minute period, levels can fluctuate 8-fold in just this hour and a half timespan!
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One study found highs and lows from 2.3 ng/mL all the way up to 40.1 ng/mL throughout a single day… all from the SAME (healthy) woman!⁣
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So what does that mean?⁣
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It means that you could go get your blood drawn at 8 am and get a result of … let’s say…11 ng/mL, while at 10 am, it may have been 30 ng/mL (or vice versa)! ⁣
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Ideally, you’d get your blood drawn multiple times throughout the day and take the average. But who wants to go get needle stabbed 5 times a day…? Not very practical!⁣
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So we’re left with trying to interpret just a single value. And that’s hard to do. We don’t know if your blood was taken at a time where a pulse of progesterone was *just* released, or if it’s close to a low point of the day. ⁣
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That’s why you can’t compare one single value. Not between women and not even between your own cycles. ⁣
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References:⁣
Filicora et al. 1984. Neuroendocrine regulation of the corpus luteum in the human. Evidence for pulsatile progesterone secretion. doi: 10.1172/JCI111370.
Mesen et al. 2015. Progesterone and the luteal phase: a requisite to reproduction. doi: 10.1016/j.ogc.2014.10.003