Prevalence and predictive factors of testosterone-induced erythrocytosis: a retrospective single center study.

Hematocrit values increased significantly from baseline to last follow-up in all patients receiving testosterone replacement therapy.

• In all patients (n=92), HCT increased by +0.04 (95% CI [0.027, 0.050], p<0.0001) compared to baseline.
• In the testosterone undecanoate group (n=71), HCT increased by +0.06 (95% CI [0.031, 0.057], p<0.0001) compared to baseline.
• Median age of the 247 included patients was 47.0 years (IQR 32-60) with a median follow-up of 2.9 years (IQR 1.0-5.5).
• TRT formulations used were testosterone undecanoate (n=194), testosterone enanthate (n=18), and testosterone gel (n=35).

A majority of patients on testosterone replacement therapy reached hematocrit values above the threshold of 0.46.

• 57% of patients reached an HCT value >0.46.
• 23% of patients reached an HCT value >0.50.
• 5% of patients reached an HCT value >0.54.
• 46% of patients who reached an HCT value >0.46 had their highest HCT measurement within the first year of TRT application.

BMI was significantly associated with the development of testosterone-induced erythrocytosis.

• Logistic regression analysis indicated that BMI was significantly associated with the development of HCT ≥0.50 (p=0.013).
• BMI was also significantly associated with the development of HCT ≥0.46 (p=0.008).
• The direction of the BMI association is not explicitly stated in the abstract but was identified as a predictive factor in risk stratification.

Baseline hematocrit was significantly associated with the likelihood of developing testosterone-induced erythrocytosis.

• There was a significant association between baseline HCT measurement and the outcome of HCT ≥0.46 (p=0.025).
• Patients with high starting HCT values were more likely to develop TIE.
• Baseline HCT was identified as a factor that should be considered in risk stratification for TIE development.

The most common indication for testosterone replacement therapy in this cohort was central hypogonadism.

• Central hypogonadism accounted for 51% of TRT indications.
• Primary hypogonadism was the second most common indication at 26%.
• The study was a retrospective single-center observational study including 247 patients.

Testosterone-induced erythrocytosis does not occur exclusively within the first year of therapy, suggesting the need for ongoing monitoring.

• Only 46% of patients who reached HCT >0.46 had their highest HCT measurement within the first year of TRT.
• The authors recommend close follow-up of laboratory values within the first year followed by annual controls.
• TIE was described as 'frequent' based on the prevalence data observed in this cohort.