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Introduction: Erythrocytosis may be the most common complication of testosterone therapy (TTh) and guidelines recommend intervention for HCT over 54. Few clinical studies have examined the risk of erythrocytosis during TTh and the influence of treatment modality and body composition is not known.
Materials & Methods: Retrospective chart review identified 171 men who underwent TTh with topical gel, injections, or pellets and 146 men maintained a single treatment modality. Linear regression modeling was used to determine factors that correlate with changes in HCT for 76 men with adequate lab and body composition data.
Results: During the first year of therapy, 2 (7.4%) and 0 of 27 patients on topical therapy developed HCT > 50 and 54 respectively compared to 21 (29.2%) and 3 (4.2%) of 72 on injections (p=0.03;0.56) and 13 (27.7%) and 2 (4.3%) of 47 on pellets (p=0.0411;0.53). For those without erythrocytosis during the first year, 4 (3.8%) patients subsequently developed HCT over 54. Increased age (p=0.0238), low baseline HCT (p=0.0034), and elevated T during therapy (p=0.5463) correlate with greater increases in HCT. Increased baseline fat percentage is associated with maximum HCT during therapy (p=0.048) but a response in terms of body composition is not related to a response in HCT.
Conclusions: Topical therapies have a lower risk of erythrocytosis compared to other modalities. Older and obese patients may be a greater risk for erythrocytosis. Until the clinical implications of erythrocytosis are better understood, HCT should be monitored during the duration of testosterone therapy.