Hormones
Bloods for Gynaecomastia: Which Blood Tests, and Why
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed June 20266 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
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Gynaecomastia is confirmed by examination, not a blood test. Bloods look for the cause. The usual set is testosterone, oestradiol, LH, FSH, prolactin and DHEA-S, plus liver, kidney and thyroid function. A hard, one-sided or fast-growing lump needs a GP before any test.
You have noticed breast tissue that was not there before. It is hard to raise with anyone. It is also very common. One review found studies reporting it in 32 to 65% of men.
Most cases are harmless. Because hormones usually sit behind it, though, a blood test is a sensible way to look for the cause.
By Helvy Medical Team · 6 min read
1. Is it gynaecomastia or chest fat?
Start here, because the two need different next steps. True gynaecomastia is growth of the gland, the firm tissue that sits right behind the nipple. It feels like a rubbery disc. It can be tender, and it can be on one side only.
“Gynaecomastia is where men have bigger breasts than usual.”
NHS, Gynaecomastia
Chest fat is different. It feels soft, spreads evenly and is not centred on the nipple. Doctors call it pseudogynaecomastia. It follows body fat rather than a hormone signal, so the blood tests below matter most for the firm, gland type. Only an examination settles which one you have.
2. Why does breast tissue grow in men?
It comes down to a balance. Oestrogen makes breast tissue grow. Testosterone holds it back. Men make a little oestrogen all the time, much of it converted from testosterone in fat tissue.
When that balance tips, the gland grows. Oestrogen can rise, testosterone can fall, or both can shift a little. That is why one hormone on its own can look normal while the pair still explains what you see. It is also why testosterone drifting down with age makes gynaecomastia more common from middle age.
3. Which blood tests are checked for gynaecomastia?
There is no single gynaecomastia test. A 2014 review in the Indian Journal of Endocrinology and Metabolism says the workup must include liver, kidney and thyroid function, as well as the sex hormones. Take the sample in the morning, when testosterone is highest.
| Marker | Why it is checked |
|---|---|
| Testosterone | Low levels weaken the brake on breast tissue. |
| SHBG | The protein that binds testosterone. High SHBG leaves less of it free to work. |
| Oestradiol | The main oestrogen in men, and the signal that makes the gland grow. |
| LH and FSH | Messages from the brain to the testes. They show where a low testosterone starts. |
| Prolactin | A pituitary hormone. When it runs high it pushes testosterone down. |
| DHEA-S | A hormone from the adrenal glands, checked for a rarer cause. |
| Liver, kidney and thyroid | Each one, when it is not working well, can tip the hormone balance. |
Here is what we can and cannot cover. Our Complete Male Hormones panel (£119) reads testosterone, SHBG, LH, FSH, prolactin and DHEA-S from one sample, with free testosterone calculated from them. Our Thyroid & Vital Organs panel (£159) adds the thyroid, kidney and liver side.
Oestradiol is not in any Helvy panel, and neither are hCG or AFP. If a clinician wants those, ask your GP.
4. What can the results point to?
Low testosterone. This is one of the commonest reasons the balance tips. Read total testosterone next to SHBG. A man with high SHBG can have a normal total and still have little free testosterone to use. Our guide to low testosterone symptoms puts the number in context.
High prolactin. Prolactin suppresses testosterone. A result that stays high on a repeat test can come from a small, non-cancerous pituitary growth, which is treatable once found. Our guide to normal prolactin levels covers the unit trap that makes some results look alarming, and high prolactin levels explains the lab artefact ruled out before anyone investigates.
Thyroid, liver or kidney. The NHS names an overactive thyroid, kidney disease and cirrhosis among the causes. Each changes how your body makes or clears hormones. If every marker comes back in range, that is reassuring too. It points towards body fat or a medicine instead.
5. Could a medicine or steroids be the cause?
Often, yes. The 2014 review found medicines behind up to 25% of cases. Its list includes spironolactone, some heart and blood pressure tablets, some prostate cancer treatments, older stomach acid tablets such as cimetidine, and some older antidepressants. Never stop a prescribed medicine yourself. Ask the person who prescribed it.
Anabolic steroids are a known cause in men who train. Your body turns part of the extra testosterone into oestrogen. Cannabis is on the review's list too. Tell your clinician honestly, because it changes how every result is read.
6. When should a GP see you first?
Before any blood test, if the lump is hard, fixed, growing fast or on one side only. The same goes for a nipple that is pulled in, leaks, or has skin changes around it. Breast cancer in men is rare, and these are the signs that need checking quickly.
NICE guideline NG12 tells GPs to refer anyone aged 30 or over with an unexplained breast lump on the suspected cancer pathway. See a GP as well if the growth came on suddenly, followed a new medicine, or came with a lump or swelling in a testicle.
See the hormone balance, not just the symptom.
Read testosterone, SHBG, prolactin and the pituitary hormones together, then add thyroid, kidney and liver if you want the wider picture. Samples go to UKAS-accredited UK labs.
Frequently asked questions
Can a blood test diagnose gynaecomastia?
No. Gynaecomastia is confirmed by examination, when a clinician feels firm gland tissue behind the nipple. Blood tests look for the cause, such as low testosterone, high prolactin or a thyroid, liver or kidney problem.
What bloods are done for gynaecomastia?
Usually testosterone, oestradiol, LH, FSH, prolactin, SHBG and DHEA-S, with liver, kidney and thyroid function. A 2014 review in the Indian Journal of Endocrinology and Metabolism also lists hCG and AFP, which a GP arranges.
Is gynaecomastia caused by low testosterone or high oestrogen?
Usually the balance between them. Oestrogen makes breast tissue grow and testosterone holds it back, so the tissue can grow when oestrogen rises, when testosterone falls, or when both shift a little.
Should I fast before the blood test?
Fasting matters less than the time of day. Testosterone is highest in the early morning, so take the sample in the morning. Fasting only matters if the same sample also checks cholesterol.
Does gynaecomastia go away on its own?
In teenagers it usually does. A 2014 review found 85 to 90% of cases in puberty settle within six months to two years. In adults it is more likely to stay unless the cause, such as a medicine, is dealt with.
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