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!
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!
So what does that mean?
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)!
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!
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.
That’s why you can’t compare one single value. Not between women and not even between your own cycles.
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