High haemoglobin: what it means and what to do

A high haemoglobin usually does not mean a blood disease. More often too little water at the blood draw, smoking, living in the mountains or testosterone is behind it. To tell whether it needs looking into, doctors check haematocrit, and the test is repeated well hydrated.

What high haemoglobin means

It means there is more haemoglobin in your blood than usual. Often there are not more red cells: there is just less water, for example if you did not drink before the blood test.

When there really are more red cells, your body is usually responding to something: less oxygen, from smoking, altitude or sleep apnoea, or testosterone. Only rarely does the bone marrow make too many on its own.

What causes high haemoglobin

The first ones usually do not mean a blood disease.

Symptoms

Usually none: it is often found by chance, on a blood test.

When the blood really is too thick, headaches, dizziness or a very red face can appear. Strong itching after a hot shower is rare, but tell your doctor: it can be a sign of polycythaemia vera.

High haemoglobin and testosterone

For people on testosterone therapy it is one of the most common side effects: testosterone pushes the bone marrow to make more red cells, so haemoglobin and haematocrit rise. The same happens with anabolic steroids.

If you are on treatment, do not change the dose on your own: tell the doctor who follows you, who looks at your haematocrit and decides what to do. If you use anabolic steroids, tell them anyway: it helps read the result correctly.

Which tests to read alongside it

These tests help show whether there really are too many red cells.

What your result means

The upper end of the scale, in g/dL. If it is high, check your haematocrit too.

What to do if it is high

It usually starts with a second test, done properly. Where to start:

When to worry

Talk to a doctor if:

With Rosa, a haematocrit above 52 in men or above 48 in women is always flagged to a doctor, above 56 urgently.

Frequently asked questions

Slightly high haemoglobin: should I worry? Usually not, if your haematocrit is below 52 in men or 48 in women. Too little water or smoking are often behind it: repeat the test well hydrated.

Is high haemoglobin dangerous? Not by itself: it is a signal. If there really are too many red cells for a long time, the blood gets thicker, which is why a high haematocrit needs a doctor’s care.

High haemoglobin and high haematocrit: what does it mean? They usually rise together, because they measure red cells in different ways. If they stay high on a second, well hydrated test, your doctor looks for the reason.

Does drinking more water lower haemoglobin? If it was high because you were dehydrated, yes: it comes back to normal once you drink normally. If there really are more red cells, water is not enough.

Does giving blood lower it? Yes, for a while. But do not do it on your own: the cause needs finding first, and if blood needs to be removed, your doctor decides.

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