What Causes High Hemoglobin?

Avoir Chaud

Haemoglobin, found in red blood cells, transports oxygen throughout the body from the lungs. The production of haemoglobin happens in the bone marrow, which should also regulate the amount it produces. A low haemoglobin level, a condition known as anaemia, is fairly common and has serious effects. High haemoglobin is also problematic, though, as it causes blood to become viscous, inhibiting the flow of oxygen throughout the body and often causes clots. Here is a list of the most common causes of elevated haemoglobin levels.

Blood Test

A simple blood test is all it takes to find out if your haemoglobin levels are normal. A high count suggests that red blood cell production has increased to compensate for lower levels of oxygen in the blood. It is possible to receive falsely elevated results if the plasma is contracted, making it seem as if there are too many red blood cells.


The most common reason for falsely high results is dehydration. If you are dehydrated at the time of the test, your haemoglobin levels may be falsely elevated. If this is the case, haemoglobin levels will return to normal upon proper hydration.

High Altitudes

At higher altitudes, the air's oxygen level goes down. To cope, the body produces extra haemoglobin so it can maximise the amount of oxygen it binds to.


Although the mechanism hasn't quite been worked out, smokers have a tendency to have elevated haemoglobin levels. A theory is that smokers' lungs have a lower level of clean oxygen. Regardless of the reason, there is a higher incidence among smokers of high haemoglobin than non-smokers.

Anabolic Steroids

An extremely common cause is the use of anabolic steroids, as they stimulate bone marrow to produce red blood cells.

EPO Doping

Injecting erythropoietin (EPO) to enhance athletic performance can also cause high haemoglobin levels. The fact that this medication, which stimulates the production of red blood cells, is used to treat anaemia is a sure sign that it can raise the haemoglobin levels of a healthy person to excess.

Other Causes

Less commonly, high haemoglobin levels are caused by more serious conditions. Among these are congenital heart disease (which you are born with), cor pulmonale (when the right ventricle of the heart becomes enlarged due to high blood pressure in your lungs), pulmonary fibrosis (when scar tissue forms between the alveoli in your lungs), hypoxia (when the blood's oxygen levels are too low), and polycythemia vera (a rare bone marrow disease in which excess red blood cells are produced). Other types of heart and lung diseases in addition to exposure to toxins are all possible (but rare) causes of elevated haemoglobin levels.

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