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FSH, LH and oestradiol: what each hormone test tells the fertility team
FSH, LH and oestradiol are three hormone blood tests usually taken together, but each does a different job. FSH shows how hard the brain is signalling the ovaries. Oestradiol helps the team read the FSH value. LH matters most when PCOS is a possibility. None is read alone: the team puts them next to the scan and your history.
This page explains what each test means. Which tests a couple needs, and on which day of the cycle, is covered on our page about fertility tests for couples, and the laboratory that runs them is described on our fertility laboratory page.
How do the brain and the ovaries talk to each other?
A small gland at the base of the brain, the pituitary, sends two messenger hormones into the blood: FSH (follicle-stimulating hormone) and LH (luteinising hormone). They travel to the ovaries and tell the small follicles there to grow and, later, to release an egg. As a follicle grows it makes oestradiol, a form of oestrogen, and the brain listens to that oestradiol to decide how hard it needs to keep signalling. It is a conversation, and a single blood test catches only one moment of it.
What does the FSH test tell the team?
FSH is a measure of effort. When the ovaries answer easily, the brain does not need to push hard, and FSH stays modest. When the ovaries answer less readily, often because fewer eggs remain, the brain pushes harder and FSH rises. So FSH gives the team an indirect view of the egg reserve, seen from the brain's side.
FSH can vary from one cycle to the next, so one result is a snapshot, not a verdict. It is usually read together with AMH and the antral follicle count on the scan, which look at the egg reserve from other angles. What AMH means at different ages is on our page on AMH level by age.
Why is oestradiol checked with FSH?
Oestradiol is the hormone that helps the team trust the FSH value. If oestradiol is already raised early in the cycle, it can hold FSH down and make it look lower than it really is. Reading the two together stops a reassuring-looking FSH from hiding a slower ovarian response. Oestradiol also gives a sense of whether a follicle or a cyst has started working earlier than expected in that cycle, which the scan can then confirm.
What does the LH test add?
LH is read alongside FSH rather than on its own. In many women with polycystic ovaries, LH runs higher than FSH, and that pattern, together with the cycle history and the scan, helps the team think about PCOS. A higher LH on its own does not make the diagnosis; it is one piece of the picture.
LH also has a second job later in the cycle: a sudden rise, the LH surge, is the signal that releases the egg. That use of LH belongs to tracking ovulation, which is explained on our page on ovulation induction.
What do FSH, LH and oestradiol results mean together?
A hormone value on a report is only a number until it is placed next to everything else: your age, your cycle pattern, the scan, AMH, your partner's semen report and any treatment already tried. Two women with the same FSH can need quite different plans. That is why the team explains the results to you in person instead of leaving you with the printed report and a search engine. Please do not change any medicine or treatment because of one value; bring the report to your appointment.
When are these tests taken?
They are usually taken early in the cycle, in the first few days of the period; the day for each test is set out on our fertility tests page.
Where are the tests done?
FSH, LH and oestradiol run on automated analysers in the fertility laboratory in Goa, and quality-control samples with known values are run every day before patient reports are released. Most fertility hormone tests need no fasting. Some tests run at set times; ask the lab when your report will be ready. To arrange a sample, including collection from home, use the Call Lab button on this page. APPOINTMENTS ARE COMPULSORY FOR DOCTOR CONSULTATION.
Questions about FSH, LH and oestradiol tests
What is the difference between FSH and LH?
Both come from the pituitary gland in the brain and act on the ovaries. FSH mainly tells the follicles to grow, and it shows how hard the brain is signalling the ovaries. LH is read alongside FSH, especially when PCOS is a possibility, and later in the cycle its surge releases the egg.
Why is oestradiol tested together with FSH?
A raised oestradiol early in the cycle can hold FSH down and make it look lower than it really is. Reading the two together helps the fertility team interpret the FSH value correctly.
Does a high FSH mean I cannot get pregnant?
Not on its own. FSH gives an indirect view of the egg reserve and can vary from cycle to cycle. It is read together with AMH, the scan and your history, and it mainly helps the team plan treatment. Your doctor will explain what your own result means.
Does a high LH mean I have PCOS?
Not on its own. A higher LH than FSH is seen in many women with polycystic ovaries, but PCOS is diagnosed from the cycle history, the scan and other findings together, not from one blood test.
When in my cycle should FSH, LH and oestradiol be tested?
They are usually taken early in the cycle, in the first few days of the period. The timing of each fertility test is set out on our fertility tests page.
Do I need to fast for these hormone tests?
Most fertility hormone tests, including FSH, LH and oestradiol, need no fasting. If a test on your form does, you are told when you book.
How soon will the FSH, LH and oestradiol report be ready?
The tests run on automated analysers in the fertility laboratory. Some tests run at set times; ask the lab when your report will be ready.
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What you read here explains fertility care in general terms and cannot replace a consultation. Decisions about your own care should be made with a doctor who knows your history and has seen you. We do not carry out or offer sex determination of any kind, which is prohibited by law in India under the PCPNDT Act.