Progesterone too high or too low: your result by cycle phase

This test measures the progesterone released after ovulation, in nanomoles per litre (nmol/l). The corpus luteum, what remains of the follicle, produces the hormone in the second half of the cycle, which is why you read the result by cycle phase. The luteal phase is the benchmark and runs from 13.1 to 46.3 nmol/l. Before ovulation the level stays below 0.62 nmol/l, and during ovulation itself it sits between 0.18 and 13.2 nmol/l. In men the upper limit is 0.47 nmol/l, after menopause 0.4 nmol/l; neither group has a lower bound, because their normal values fall below the detection limit of 0.159 nmol/l and the lab reports them as less than that limit. These bands do not apply in pregnancy, because progesterone then rises far above the luteal range. The numbers belong to the Roche Elecsys method.

For an athlete this hormone is interesting for two reasons. It lifts your basal body temperature in the second half of the cycle by a few tenths of a degree and slightly raises resting ventilation, which is why a temperature chart shows ovulation after the fact. And it is sensitive to your energy balance: an energy intake too low for the load suppresses ovulation, and luteal progesterone then stays low while the period sometimes still arrives as usual.

Draw the sample seven days before the expected period and not on a fixed day, because the second half of the cycle is a fairly constant fourteen days and the first half varies. The hormone comes out in pulses, so a borderline result needs a repeat. On hormonal contraception the result stays low because no ovulation occurs; that is the method and not a finding.

For a woman who trains a great deal, progesterone is the earliest measurable sign that energy availability is too low: what is left over once the training has been paid for. The body then economises on reproduction first. Ovulation stops, no corpus luteum forms and luteal progesterone stays low, often for cycles before the period itself disappears. Such a cycle without ovulation can carry an ordinary bleed and feels no different, which is exactly why it is missed.

That is why a low progesterone on the right day in an athlete is not read as a free-standing hormone problem. It is a signal about the balance between intake and load, and it belongs to the wider question of low energy availability, with consequences for bone density, recovery and injury risk. A low value is therefore a reason to look at the energy balance, together with a sports physician or dietitian, and not a reason to want to top up progesterone.

The second reason to know the hormone is its effect on your physiology in the luteal phase. Progesterone raises core temperature by roughly 0.3 to 0.5 degrees, raises resting ventilation and shifts fluid balance, so heat weighs a little heavier in that phase. How much that matters for performance is modest and differs between individuals; the evidence that periodising training by cycle phase produces better results is weak. Track your own cycle and your own experience, and draw no conclusions from an average.

What you do not read from it: a precise threshold above which ovulation is proven. The figures circulating for that appear in no current guideline and therefore not on this page. In a regular cycle of normal length the Dutch GP standard advises against the test, because such a cycle already points strongly to ovulation on its own. If ovulation keeps failing to occur, your FSH, LH and oestradiol at the start of the cycle belong alongside, and your TSH and ferritin as the wider picture of an energy balance that is too tight.

Draw seven days before the day you expect your period, in the middle of the luteal phase. Count back from the end of the cycle: at 28 days that is day 21, at 35 days day 28. A fixed day 21 in a longer cycle still measures the first half and produces a low value that means nothing. So note after the draw when the period actually came; if it came more than ten days later, the timing was too early and you repeat the test in a following cycle.

Timing relative to training matters little for progesterone: one hard session does not shift the value the way it shifts CRP or CK. What does matter is the period. A training camp, a competition block or a spell of deliberate weight loss can suppress ovulation in that cycle, and you then measure the effect of that block rather than your usual pattern. If you want to know what your cycle normally looks like, draw in a quieter period; if you want to know what a heavy block does to your ovulation, draw during the block and compare.

With an irregular cycle a urine ovulation test helps you choose the moment: draw six to eight days after a positive test. Fasting is not needed. On hormonal contraception that suppresses ovulation the test is not informative. If you take progesterone as a medicine, say so, because the test measures it too. And if you may be pregnant, you are no longer measuring a cycle phase and your doctor or midwife assesses the result.