ODP412 High Frequency of Erythrocytosis in Hypogonadal Men on Testosterone Replacement Therapy

INTRODUCTION: Erythrocytosis is a frequent side effect of testosterone replacement therapy (TRT) in hypogonadal males and can be deleterious by increasing blood viscosity, which can lead to headaches, hypertension, and thromboembolic complications. Main causes of erythrocytosis are short-acting testosterone injections, smoking habit and obesity. AIM: Study the frequency of erythrocytosis induced by TRT and its predictive factors in hypogonadal men in our setting. Subjects and methods: A retrospective study in hypogonadal males on TRT for at least 3 months was conducted. Age, age at treatment onset, months on treatment, initial hematocrit (IHt), highest hematocrit during follow-up (MaxHt), hematocrit on last visit (FHt), hematocrit increase (HtIn), maximum hematocrit increase (HtMaxIn), anthropometric measures, sex hormones and biochemical parameters on the last visit were recorded. In addition, testosterone formulation, smoking status, dyslipidemia, hypertension, diabetes, type of hypogonadism and presence of cardiovascular disease (CVD) were also documented. A hematocrit ≥ 50% (Ht≥50) was considered erythrocytosis and one ≥ 53% was indication for phlebotomy (Ht≥53). RESULTS: 108 patients were included, age 54 ± 19 years, age at THT onset 44 ± 18 years, BMI 30 ± 5 Kg/m 2 . On the last visit, 29% had FHt≥50 and 11% had FHt≥53, while during follow-up 58% had MaxHt≥50 and 35% had MaxHt≥53. Moreover, 18% were smokers, 61% had dyslipidemia, 48% had hypertension, 36% were diabetic, 59% were on short acting IM testosterone injections (cypionate), 25% were on extended-release IM testosterone injections (undecanoate) and 16% were on transdermal testosterone. On the other hand, 13% had CVD at onset and 6% developed CVD during follow-up. None of the hematocrit or hematocrit increase values was related to the type of testosterone formulation, smoking habit or appearance of CVD during follow-up. They also did not correlate with serum total testosterone, other sexual hormones and lipids levels or BMI. Interestingly, there was no difference in total testosterone levels between the three testosterone preparations groups. FHt (44 vs 48%, p=0,018) and HtIn values (1.86 vs 5.31%, p=0,036) were lower in those with previous CVD disease. This fact cannot be explained by BMI since there was no difference between patients with and without CVD. Although it could be due to a lower percentage of smokers in the group of patients with CVD, that could not be demonstrated. DISCUSSION: The occurrence of erythrocytosis secondary to TRT in hypogonadal men in our setting was very common and higher than reported previously: 58% of patients during follow-up and 35% required phlebotomy. Hematocrit and hematocrit increase values were independent of BMI, smoking status, type of testosterone formulation and presence of CVD. This lack of association could be due in part to the small number of individuals in some of the subgroups. Presentation: No date and time listed