Oestradiol in men: why it is measured and what high or low levels mean

Many men are surprised to see oestradiol on their blood results. It is the main form of oestrogen, and it is usually discussed as a women's hormone. But men make it too, and the right amount matters for their health. The Well Man panel measures it alongside testosterone because the two are closely linked.

Where oestradiol in men comes from

In men, most oestradiol is made from testosterone. An enzyme called aromatase, found mainly in fat tissue but also in the brain, bone and elsewhere, converts a small share of testosterone into oestradiol. The testes make a little directly as well.

This means oestradiol usually rises and falls with testosterone. It also means that the more body fat a man carries, the more testosterone tends to be converted.

What oestradiol does in men

• Keeps bones strong. In men, oestradiol is one of the main hormones that protects against bone loss.
• Supports sex drive and erections, together with testosterone.
• Plays a part in body fat distribution, cholesterol and blood sugar control.
• Affects mood and brain function.

So the goal is not the lowest possible oestradiol. It is a level that is in balance with testosterone.

How LifePrint reads the result

There is no guideline cut-off for oestradiol in men. Normal ranges depend on the lab's method, so LifePrint uses the range printed on your lab report. Results in men are reported in pmol/L.

One technical point is worth knowing. The standard lab tests for oestradiol were designed for the much higher levels seen in women. At the low levels found in men, some of these tests are less precise, and a result can be slightly off. For that reason, a single borderline oestradiol in a man should be read with caution and in context.

What a high oestradiol can mean

A mildly raised oestradiol is common and often has a simple explanation. Causes include:

• Excess body fat, which increases the conversion of testosterone.
• Heavy alcohol use and liver disease, which change how hormones are broken down.
• Testosterone therapy or anabolic steroids, which provide more testosterone to convert.
• An overactive thyroid.
• Some medicines.
• Rarely, a hormone-producing tumour of the testes or adrenal glands.

The most common symptom of high oestradiol in men is gynaecomastia, which is swelling or tenderness of breast tissue. Low sex drive and erection problems can occur too.

What a low oestradiol can mean

Low oestradiol in men usually goes hand in hand with low testosterone, because there is less testosterone to convert. It can also follow treatment that blocks oestrogen or aromatase. Over time, low oestradiol can contribute to bone thinning, low sex drive and hot flushes. If your oestradiol is low, it is worth looking at your testosterone and SHBG results on the same report.

Reading oestradiol with testosterone

Oestradiol means little on its own. The Well Man panel measures it together with total testosterone, SHBG and calculated free testosterone, so the whole hormone picture can be seen at once. For example, a high oestradiol with a low testosterone in a man carrying extra weight tells a very different story from a high oestradiol in a man taking testosterone. Our article on testing testosterone explains how to get a reliable testosterone result.

What to do with your result

Do not try to treat an oestradiol result yourself. Products marketed to lower oestrogen can push levels too low and harm bone health. If your oestradiol is flagged, or if you have breast swelling, low libido or other symptoms, discuss your results with a registered healthcare practitioner. Your LifePrint report explains the result and how urgently to follow up. It is health information, not a diagnosis.