Fertility hormone tests: FSH, LH, estradiol and progesterone
Understand when fertility hormone tests are requested, why cycle timing matters and the roles of FSH, LH, estradiol, progesterone, TSH and prolactin.
Fertility hormone tests can help explain ovulation and menstrual function, but every hormone is not necessary for every patient. Selection depends on cycle regularity, absent periods, symptoms, age and the treatment being considered. The same laboratory value can have a different meaning on different cycle days.
FSH, LH, estradiol and progesterone provide information about different stages of reproductive function. TSH and prolactin are investigated when cycle patterns or symptoms suggest a reason. Results should be interpreted according to timing and purpose rather than compared with one universal “normal” number online.
Why are FSH, LH and estradiol measured?
FSH and LH come from the pituitary and are part of the signalling that controls follicle growth and ovulation. Estradiol is produced by developing follicles. In absent or very irregular periods, their combined pattern can help distinguish ovarian insufficiency, hypothalamic-pituitary causes and patterns associated with PCOS.
Baseline tests may be requested early in the cycle, although FSH is no longer considered as useful as AMH or AFC for predicting ovarian response in IVF. Each analysis should answer a defined clinical question.
- Cycle day can change the meaning of a laboratory value.
- One isolated hormone result does not establish a diagnosis.
- Symptoms, ultrasound and history are interpreted together.
How does progesterone assess ovulation?
Progesterone rises after ovulation and, when measured at the appropriate time, can help confirm recent ovulation. Giving everyone a test on “day 21” is inaccurate; timing should relate to expected menstruation and the individual cycle length.
A single progesterone value does not determine the quality of the entire luteal phase or the chance of pregnancy. With irregular cycles, repeat measurement, ultrasound or another method may be needed to identify suitable timing.
TSH, prolactin and purposeful test selection
Thyroid function can affect cycles, while elevated prolactin can disrupt ovulation. These tests are particularly relevant with absent periods, galactorrhoea, thyroid symptoms or another clinical indication. Stress and certain medicines can temporarily raise prolactin, so an unexpected result may need confirmation.
The goal is to identify a possible endocrine cause, not to measure every hormone without direction. The clinician should review medicines and supplements, and a patient should never stop a prescribed medicine without appropriate advice.
Frequently asked questions
Are all hormone tests performed on the same cycle day?
No. Timing differs by purpose. Baseline hormones are often measured early in the cycle, while progesterone is assessed after expected ovulation. The clinician should specify your day.
Do normal hormone results rule out a fertility problem?
No. Tubal, uterine, endometriosis, age-related, sperm and other factors can exist with normal hormones. A fertility assessment considers the whole clinical picture.
To plan fertility hormone tests at the right cycle time and for a clear clinical reason, discuss your history and existing results with the Övlad Payı team.
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This article is for patient education and does not replace individual medical advice.
