Progesterone Above or Below the Normal Range: Causes in Athletes and What to Do
Progesterone is one of the hormones most often misread on blood test reports. A "low" value can be completely normal if the sample was taken on the wrong day of the cycle, while a genuinely low luteal-phase level may signal that training and nutrition are out of balance. Our editorial team explains how to interpret results in athletes and what to do next.
What progesterone does
Progesterone is a steroid hormone produced mainly by the corpus luteum, the structure that forms in the ovary after ovulation. Smaller amounts come from the adrenal glands, and in pregnancy the placenta becomes the main source.
In women, progesterone prepares the lining of the womb for a possible pregnancy, raises body temperature slightly after ovulation, influences breathing and fluid balance, and interacts with oestrogen effects on bone, mood and metabolism.
Levels vary enormously across the menstrual cycle. They are low in the follicular phase before ovulation and rise sharply in the luteal phase, peaking about a week after ovulation. Without that cyclical change, interpreting a single result is impossible.
Men also produce small amounts of progesterone, mainly from the adrenal glands and testes. It is a precursor for other steroid hormones, and its levels are normally low and fairly stable.
How to interpret a result correctly
In the UK, progesterone is usually measured in nanomoles per litre (nmol/L). To confirm ovulation, NICE fertility guidance recommends testing in the mid-luteal phase, about seven days before the expected period. For a 28-day cycle this is day 21; for a 35-day cycle it would be around day 28.
A mid-luteal level above roughly 30 nmol/L is generally taken as evidence that ovulation occurred. A lower result may mean anovulation, a weak luteal phase, or simply that the sample was taken too early or too late in that particular cycle.
| Situation | Typical progesterone pattern | Comment |
|---|---|---|
| Follicular phase | Low | Normal; a "low" result here is expected |
| Mid-luteal phase after ovulation | Clearly raised | Used to confirm ovulation |
| Anovulatory cycle | Stays low all cycle | Common in low energy availability or PCOS |
| Hormonal contraception | Usually low endogenous levels | Pills, implants and IUS suppress ovulation |
| Pregnancy | High and rising | Always consider pregnancy if unexpectedly high |
Hormonal contraceptives complicate interpretation. Most prevent ovulation, so endogenous progesterone stays low; some synthetic progestogens are not detected by standard assays. Always tell the clinician what contraception you use.
One test rarely tells the full story. Doctors usually look at cycle history, LH, FSH, oestradiol, prolactin, thyroid function and sometimes testosterone, and may repeat tests over more than one cycle before reaching conclusions.
Low progesterone: why it happens in athletes
The most common reason for low progesterone in active women is low energy availability, where energy intake does not cover both training and basic body functions. The brain responds by reducing the pulsatile release of gonadotrophins, and ovulation becomes less reliable.
Loucks and Thuma demonstrated in 2003 that LH pulsatility is disrupted when energy availability falls below a threshold. De Souza and colleagues later showed that subtle menstrual disturbances, including luteal phase defects and anovulation, are surprisingly common among exercising women with apparently regular cycles.
- Relative Energy Deficiency in Sport (REDs): under-fuelling relative to training load;
- Functional hypothalamic amenorrhoea: missed periods linked to energy deficit, stress or weight loss;
- Polycystic ovary syndrome: irregular or absent ovulation with other metabolic features;
- Thyroid disorders and high prolactin: both can disrupt ovulation;
- Perimenopause: increasingly frequent anovulatory cycles from the late thirties onwards.
The 2023 IOC consensus on REDs describes how these hormonal changes can affect bone health, metabolism, immunity and performance. Low progesterone and oestrogen together increase the risk of stress fractures and low bone density over time.
Short luteal phases or absent ovulation are not only a fertility issue. For athletes, they can be an early warning that the overall training and nutrition balance needs to change before more serious problems develop.
High progesterone: possible causes
The most common cause of a high progesterone result is simply that the test was taken in the luteal phase, when high levels are expected. The next most important consideration is pregnancy, which should be ruled out when a result is unexpectedly high.
Less often, raised progesterone or its precursor 17-hydroxyprogesterone may point to adrenal disorders such as non-classic congenital adrenal hyperplasia. This condition can mimic PCOS, causing irregular periods and excess hair growth.
Some ovarian cysts and, rarely, adrenal or ovarian tumours can produce progesterone. Fertility treatments and progesterone medication used in pregnancy or for menstrual problems also raise measured levels.
In men, raised progesterone is uncommon and may be related to adrenal disorders or certain medicines. Some anabolic steroids, such as nandrolone and trenbolone, act on progesterone receptors even though they may not raise measured progesterone. Our editorial team does not provide guidance on using these drugs; anyone who has used them should inform their doctor so that symptoms and tests are interpreted correctly.
What to do next
If your progesterone result is outside the reference range, first check when the sample was taken in relation to your cycle and whether you use hormonal contraception. Many apparently abnormal results resolve once timing is considered.
For persistent low levels, missed or irregular periods, consider whether you are eating enough to support your training. A sports dietitian can estimate energy needs and help increase intake, which often restores normal cycles over several months.
Seek medical assessment if periods stop for three months or more, if you have signs of excess androgen such as acne or hair growth, symptoms of thyroid disease, or if you are trying to conceive. The Endocrine Society guideline on functional hypothalamic amenorrhoea recommends a full evaluation rather than simply prescribing hormones.
Avoid trying to fix hormone levels with over-the-counter "progesterone creams" or supplements. They are poorly standardised, may mask underlying problems and are not a treatment for REDs or anovulation.
Conclusions of the editorial team
Progesterone varies greatly across the menstrual cycle, so timing is everything. A mid-luteal test is used to confirm ovulation, while low results at other times are often normal.
In athletes, genuinely low luteal progesterone often reflects low energy availability and may be an early sign of REDs, with implications for bone and overall health.
High results are usually explained by cycle timing or pregnancy, but adrenal and ovarian causes need medical investigation. Self-treatment with hormones or creams is not appropriate.
Related reading from our editorial team includes guides on REDs in female athletes, interpreting oestradiol results, and iron deficiency in women who train.
References
- Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). Br J Sports Med. 2023;57(17):1073–1097.
- Gordon CM, Ackerman KE, Berga SL, et al. Functional hypothalamic amenorrhea: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2017;102(5):1413–1439.
- De Souza MJ, Toombs RJ, Scheid JL, et al. High prevalence of subtle and severe menstrual disturbances in exercising women: confirmation using daily hormone measures. Hum Reprod. 2010;25(2):491–503.
- Loucks AB, Thuma JR. Luteinizing hormone pulsatility is disrupted at a threshold of energy availability in regularly menstruating women. J Clin Endocrinol Metab. 2003;88(1):297–311.
- National Institute for Health and Care Excellence. Fertility problems: assessment and treatment. Clinical guideline CG156. London: NICE; 2013.
- Elliott-Sale KJ, Minahan CL, de Jonge XAKJ, et al. Methodological considerations for studies in sport and exercise science with women as participants: a working guide for standards of practice for research on women. Sports Med. 2021;51(5):843–861.
- Teede HJ, Tay CT, Laven JJE, et al. Recommendations from the 2023 international evidence-based guideline for the assessment and management of polycystic ovary syndrome. J Clin Endocrinol Metab. 2023;108(10):2447–2469.
- https://massdrivenuk.com/44-31944-trenbolone-blend-trenbolone-uk
