Background: Testosterone replacement therapy has been shown to produce a wide range of benefits for men with hypogonadism with studies showing improvement in libido, bone density, muscle mass, body composition, mood, cognition, and erythopoiesis. The risks associated with testosterone replacement therapy are less well characterised and there is a lack of larger randomised trials. One recognised risk is polycythaemia. The aim of this study is to assess the frequency of polycythaemia in men treated with testosterone and to compare its frequency with different treatment modalities.
Methods: This is a retrospective observational study. We analysed biochemical and haematological parameters of all men on testosterone therapy who attended our endocrinology unit from the 1st of January 2009 until the 30th of June 2010. Of a total of 173 men, 86 (50%) were treated with testosterone undecnoate (Nebido), 57 (33%) with transdermal testosterone gel, and 30 with intramuscular testosterone in the form of Sustanon. Data were collected on haemoglobin concentrations and packed cell volumes. Polycythaemia was defined as haemoglobin concentration >17 g/dl or packed cell volume >0.505.
Results: Out of the 173 men 25 (14.5%) developed polycythaemia on at least one blood sample during the above period. 12 of the 86 men treated with Nebido (14%), 8 out of the 57 men treated with transdermal gel (14%), and 5 of the 30 men treated with Sustanon (17%) developed polycythaemia. There was therefore no significant difference between the different treatment groups.
Conclusion: In our experience polycthaemia is a common risk with any testosterone replacement therapy. Although previous studies have indicated that this is less likely with transdermal preparations we found the risk to be equally high in all treatment groups. This demonstrates the importance of careful monitoring of haematological variables during any testosterone treatment so that appropriate measures can be taken if erythrocytosis occurs.