Prevalence and predictive factors of testosterone-induced erythrocytosis: a retrospective single center study.
Level 4 - case-series / case-control
Retrospective single-center uncontrolled observational cohort study
PubMed 39882268 · doi:10.3389/fendo.2024.1496906
What was done
A retrospective single-center observational study evaluated 247 patients receiving testosterone replacement therapy (TRT). Median age was 47.0 years (interquartile range [IQR] 32–60) and median follow-up was 2.9 years (IQR 1.0–5.5). Indications included central hypogonadism (51%) and primary hypogonadism (26%). Formulations used were testosterone undecanoate (n=194), testosterone enanthate (n=18), and testosterone gel (n=35). Researchers analyzed hematocrit (HCT) changes from baseline to last follow-up and used logistic regression to identify predictors of elevated HCT.
What was found
Hematocrit increased significantly from baseline to last follow-up by +0.04 (95% CI [0.027, 0.050], p < 0.0001; n=92) overall and by +0.06 (95% CI [0.031, 0.057], p < 0.0001; n=71) in the testosterone undecanoate group. Across follow-up, 57% of patients reached HCT > 0.46, 23% reached HCT > 0.50, and 5% reached HCT > 0.54. Of those reaching HCT > 0.46, 46% had their highest measurement within the first year of treatment. Logistic regression indicated that body mass index was significantly associated with developing HCT ≥ 0.50 (p = 0.013) and HCT ≥ 0.46 (p = 0.008). Higher baseline HCT was also significantly associated with developing HCT ≥ 0.46 (p = 0.025).
Why it matters
This study shows that testosterone-induced erythrocytosis often develops after the first year of therapy and identifies higher baseline BMI and baseline hematocrit as key clinical risk factors requiring long-term monitoring.
Limits
The study is a retrospective, single-center analysis without a control group. Paired baseline to follow-up hematocrit data were available for only 92 of 247 patients. Testosterone undecanoate accounted for 79% of prescriptions, limiting formulation comparisons, and specific regression effect sizes (odds ratios) were not reported in the abstract.
Cited by
- supports Approximately 25% of men on testosterone replacement therapy develop elevated hematocrit or polycythemia.