The Impact of Exogenous Testosterone on Haematocrit Levels

Dr Angela Servis
Dr Angela Servis
August 18, 2026
 The Impact of Exogenous Testosterone on Haematocrit Levels


Testosterone is a hormone that plays a critical role in male development and function. Exogenous testosterone, or testosterone that is administered from an external source, has become increasingly common for the treatment of hypogonadism and other medical conditions. However, exogenous testosterone can also have negative effects on haematocrit levels, which can affect cardiovascular health. This essay provides a review of the research on the impact of exogenous testosterone on haematocrit levels.


Exogenous testosterone has been found to increase haematocrit levels in some individuals. Haematocrit is a measure of the percentage of red blood cells in the blood. When haematocrit levels are too high, it can cause the blood to become thicker and more viscous, which can increase the risk of cardiovascular events such as stroke and heart attack.


The increase in haematocrit levels is thought to be due to the stimulation of erythropoietin production by testosterone. Erythropoietin is a hormone that stimulates the production of red blood cells in the bone marrow. When testosterone levels are increased, erythropoietin levels can also increase, leading to an increase in haematocrit levels.


However, not all individuals who receive exogenous testosterone experience an increase in haematocrit levels. In some cases, haematocrit levels may remain stable or even decrease. The impact of exogenous testosterone on haematocrit levels appears to be influenced by a variety of factors, including age, baseline haematocrit levels, and the dosage and duration of testosterone therapy.


Given the potential negative effects of high haematocrit levels on cardiovascular health, it is important to monitor haematocrit levels in individuals receiving exogenous testosterone. The American Association of Clinical Endocrinologists recommends monitoring haematocrit levels every 3-6 months in individuals receiving testosterone therapy.


If haematocrit levels become elevated, options for managing the condition include phlebotomy (removal of blood), dose adjustment or discontinuation of testosterone therapy, or other treatments such as erythropoiesis-stimulating agents.



Exogenous testosterone has been found to increase haematocrit levels in some individuals. High haematocrit levels can increase the risk of cardiovascular events, making monitoring haematocrit levels an important aspect of testosterone therapy. If haematocrit levels become elevated, management options include phlebotomy or dose adjustment.



Talk to an Eden Clinic doctor

This article is general information, not medical advice. If you would like your own symptoms, results or treatment options reviewed, our doctors offer private consultations in Plymouth and online.

Concerned about low testosterone?

Low testosterone is common, under-diagnosed, and treatable. Dr Angela Servis reviews every set of results herself, and the first step is a proper blood test. Questions? Call the clinic on 0333 335 6414.

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A man having a blood sample taken by a clinician at Eden Clinic