FSH, LH and Prolactin Tests: What They Tell You About Your Fertility

Quick answer

FSH, LH and prolactin are blood tests that show how well your brain is signalling your ovaries, and whether anything is interfering. They are usually taken together with TSH for thyroid function. Timing matters: FSH and LH are normally tested on day 2 or 3 of your cycle. On their own these tests do not diagnose infertility, and they are only part of the picture.

Key takeaways

• Cycle day matters. FSH and LH tested at the wrong point in the cycle can be misleading. Day 2 or 3 is standard.

• A single raised prolactin usually needs repeating. Stress, a difficult blood draw, exercise, food and even a breast examination can raise it temporarily.

• These four tests are not the full fertility workup. AMH, a day 21 progesterone, a pelvic ultrasound, a test of whether your tubes are open, and a semen analysis for your partner all matter.

• A semen analysis should be one of the first tests, not the last. It is inexpensive, quick, and male factors contribute to a large share of infertility.

• Use your own laboratory's reference range. Units and normal ranges differ between labs and assays, so the numbers on your report are what count.

What these tests actually measure

Your ovaries do not work alone. A small gland at the base of your brain, the pituitary, sends hormone signals that tell them what to do. These tests look at those signals and at anything interfering with them.

When in your cycle to test

This is the part most often got wrong, and a mistimed test wastes both money and time.

If your cycles are irregular or absent, your doctor will tell you when to test, since day 2 or 3 may not be identifiable. Our guide to causes of a delayed period covers why cycles become irregular.

Before the blood draw: tell the lab and your doctor about every medicine and supplement you take, including hormonal contraception, thyroid medication, antidepressants, anti-nausea drugs, and Ayurvedic or herbal products. Several of these affect these exact hormones.

Typical reference ranges

Use your own laboratory's ranges. Units and normal values differ between labs and assays, particularly for prolactin, which is reported in nanograms per millilitre in some labs and milli-international units per litre in others.

A number slightly outside the range is not automatically a problem, and a number inside it does not guarantee everything is fine. These results are interpreted together, alongside your cycle, your scan and your history.

What abnormal results can mean

Two things worth knowing about prolactin

A single raised result usually needs repeating. Prolactin rises temporarily with stress, a painful or difficult blood draw, exercise, sleep, food, sex and breast examination. Many mildly raised results normalise on a properly taken repeat sample.

Macroprolactin. Some people have a biologically inactive form of prolactin that shows up as a high reading but causes no symptoms and needs no treatment. If your prolactin is raised and you have no symptoms, ask whether macroprolactin has been checked before starting any medication.

Symptoms that make a genuinely raised prolactin more likely: irregular or absent periods, milky discharge from the nipples when not breastfeeding, headaches, or changes in vision.

The tests this panel does not include

This is where most people are under-tested, and it matters.

AMH and a day 21 progesterone are the two most commonly missing tests when women bring a hormone panel to a first fertility consultation. Ask about both.

Testing for men

A semen analysis should be one of the first tests a couple has, not the last.

It is inexpensive, takes days rather than cycles, and male factors contribute to a substantial proportion of infertility. Our guide to how the sample is collected and prepared explains what is involved, including the abstinence period and how to avoid a misleading result.

Hormone tests for men may include FSH, LH, testosterone and prolactin, usually after an abnormal semen analysis, to work out whether the problem is in the testes or in the brain's signalling.

One important point: testosterone supplements and anabolic steroids suppress sperm production and are a recognised cause of male infertility. If your partner has used them at any point, that needs to be disclosed, because it changes the entire investigation.

When to see a fertility specialist

Do not wait for a hormone result to decide this. Time is the factor that matters most in fertility, and it is the one thing no test recovers.

Seek help immediately, whatever your age and however long you have been trying, if:

• Your periods are irregular, very infrequent or absent

• You have been diagnosed with PCOS, endometriosis or a thyroid disorder

• You have had pelvic surgery, a pelvic infection, or an ectopic pregnancy

• You have had two or more miscarriages

• Your partner has a known sperm problem, or a history of undescended testes, testicular surgery or injury

• Either of you has had chemotherapy or radiotherapy

• You have very painful periods or pain during sex

• You have milky nipple discharge and are not breastfeeding

What Indian women should know

• Thyroid disorders are common, which is why TSH belongs in this panel. They are easily tested and easily treated

• PCOS is very common, and it is a clinical diagnosis made from cycles, symptoms, blood tests and ultrasound together, not from an LH to FSH ratio alone

• Do not order these tests yourself without interpretation. Private labs will run a fertility panel on request, and a result without context causes more anxiety than it resolves. Take every report to a doctor

• Costs vary widely. These tests are available at government hospitals and district facilities, and a basic panel in a private lab typically costs far less than a single specialist consultation

• Anaemia and vitamin B12 and D deficiency are common, particularly on vegetarian diets, and are worth checking alongside

• Keep every report in one file, with dates and cycle days written on them. Trends across cycles matter more than a single reading

After your results

• Normal results do not rule out a problem. They narrow the field, and further tests may still be needed

• Abnormal results are usually manageable. Thyroid problems, raised prolactin and PCOS all have effective treatments

• A borderline result is usually repeated rather than acted on immediately

• Take your reports to a doctor, and ask what each result means for you specifically

• Ask what the next test is, and when

Questions worth asking:

• What do these results mean in my case?

• Do any need repeating, and on which cycle day?

• Should I have AMH and a day 21 progesterone?

• Do we need an ultrasound and a tubal patency test?

• Can we arrange a semen analysis?

• Given my age and how long we have been trying, should we be seeing a fertility specialist now?

Frequently asked questions

On which day of my cycle should I do the FSH and LH test?
Day 2 or 3, counting from the first day of full flow. Your doctor will advise differently if your cycles are irregular.

Do I need to fast for these tests?
Often for prolactin, and sometimes for others. Ask your lab in advance, since protocols differ.

What does a high FSH mean?
It can indicate reduced ovarian reserve, meaning the ovaries need a stronger signal to respond. It is usually repeated in another cycle and interpreted alongside AMH and an ultrasound count.

What does a high prolactin mean?
It can suppress ovulation, but a single raised reading is often temporary. It should be repeated on a properly taken sample before anything is concluded, and macroprolactin should be checked.

Can these tests diagnose PCOS?
Not on their own. PCOS is diagnosed from cycles, symptoms, blood tests and ultrasound together.

Does a normal result mean I am fertile?
No. These tests cover part of the picture. Ovulation, tubes, uterus and sperm all need separate assessment.

Should my partner be tested too?
Yes, and early. A semen analysis is one of the most informative first tests for a couple.

What is AMH, and should I have it?
Anti-Müllerian hormone, the most widely used marker of ovarian reserve. It can be taken on any cycle day, and it is often the most useful test missing from a basic panel. Ask your doctor.

Can thyroid problems affect fertility?
Yes. Both underactive and overactive thyroid affect cycles and fertility, and both are treatable, which is why TSH is included.

How much do these tests cost in India?
Prices vary widely between private labs, and the tests are available at government facilities. Ask about the full panel cost including AMH and progesterone before booking.

The bottom line

FSH, LH, prolactin and TSH show how well your brain is signalling your ovaries and whether anything is interfering, and the timing of the blood draw changes what the numbers mean. Take them on the right cycle day, repeat a raised prolactin before acting on it, and use your own lab's reference range. Then ask about the tests that are usually missing: AMH, a day 21 progesterone, a tubal patency test, and a semen analysis for your partner. And do not let a set of results delay the specialist appointment, because time is the one part of fertility that testing cannot give back.

Sources

• National Institute for Health and Care Excellence, Fertility problems: assessment and treatment

• NHS, infertility diagnosis

• American Society for Reproductive Medicine, diagnostic evaluation of the infertile female and male

• Endocrine Society, clinical practice guideline on hyperprolactinaemia

• World Health Organization, infertility

• World Health Organization, laboratory manual for the examination and processing of human semen

• Indian Society for Assisted Reproduction, clinical practice context

• Indian Council of Medical Research, national guidelines for accreditation, supervision and regulation of ART clinics

This article is for general information and is not a substitute for professional medical advice. Take every report to your doctor for interpretation, and do not start or stop any medication based on a test result alone.

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