Hormones
Progesteron
The hormone of the second half of the cycle; shows whether ovulation has taken place, provided it is measured on the right day of the cycle.
Everything about this testWhat it measures
After ovulation, progesterone is made by the corpus luteum, the remains of the follicle that released the egg, and during pregnancy by the placenta. It prepares the lining of the uterus for implantation of a fertilized egg; if that does not happen, progesterone falls and menstruation begins. Before ovulation the value is low, and it is highest about a week after. The result therefore only has meaning together with the cycle day.
- Whether ovulation has taken place in this cycle (in fertility tests and cycle disorders)
- Cycles without ovulation, such as with PCOS, underweight, intensive exercise or in the run-up to menopause
- Additional information in early pregnancy with symptoms (can only be interpreted together with hCG)
High
A high value in the second half of the cycle is normal and means that ovulation has taken place. During pregnancy, progesterone rises sharply, and the value is also high when taking medicines that contain progesterone (for example during IVF). A raised progesterone outside these situations is rare and fits a congenital adrenal disorder or, rarely, a cyst or tumor of the ovary.
Low
A low value is normal in the first half of the cycle, when taking the pill, after menopause and in men. If the value is still low about a week after the expected ovulation, there was probably no ovulation in that cycle; this occurs with PCOS, underweight, intensive training, stress, a raised prolactin, a thyroid disorder and in the years before menopause. A single low value proves little: ovulation may have occurred later than thought, or the cycle happened to be without ovulation, which also happens a few times a year in healthy women. A 'too low' progesterone as the cause of symptoms such as tiredness or mood swings is not supported by evidence.
Preparation
- Have your blood taken about 7 days before your next period. With a 28-day cycle that is around day 21 (day 1 is the first day of your period). At any other time the result says little.
- Do you take biotin (vitamin B8, often in hair and nail supplements)? Stop at least 2 days before the sample is taken, or 4 days for a high dose.
If your result is abnormal
The GP assesses the value together with the cycle day and repeats the measurement in a following cycle at a better chosen moment if the timing was uncertain. If ovulation repeatedly does not occur, the cause is looked for (PCOS, weight, prolactin, thyroid), and with a wish to become pregnant, referral to a gynecologist follows.
Reliability
Progesterone only means something if the blood is drawn at the right moment: about seven days before the expected period, which in a 28-day cycle is around day 21. With a regular cycle, ovulation is so likely that a progesterone test adds little; with an irregular cycle, the test can help to show ovulation. One measurement says something about one cycle, not about fertility in general.
Limitations
- The cycle day: blood drawn too early or too late gives a falsely low value; with an irregular cycle, the right moment is hard to determine and several measurements are sometimes needed.
- The pill, the hormonal IUD and other hormonal contraception suppress ovulation; the result then says nothing about your own cycle.
- Medicines containing progesterone, pregnancy and biotin supplements affect the result.
- Reference values differ between laboratories and between cycle phases; the cut-off above which ovulation is considered confirmed differs between laboratories.
How common is this
About 10 to 15 in 100 couples do not manage to become pregnant within a year. In some of them, the absence of ovulation is the cause, usually due to PCOS. Cycles without ovulation also occasionally occur in healthy women, and more often in the years before menopause.
Who is this useful for
Useful with an irregular cycle and a wish to become pregnant, to show ovulation, and when assessing cycle disorders together with FSH, LH, estradiol and prolactin. With a regular cycle, the test adds little. Not useful when taking the pill, after menopause, in men, or to explain symptoms such as tiredness or PMS.
Downsides and risks
- A low value due to a wrongly chosen day for the blood draw is easily read as 'no ovulation' or 'progesterone deficiency', which can lead to unnecessary worry or unproven hormone use.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results