Research

Hormonal

Testosterone therapy in adult men significantly increases hemoglobin and hematocrit levels and decreases high-density lipoprotein (HDL) cholesterol, but does not significantly affect mortality, cardiovascular events, or prostate outcomes.

If you are considering testosterone therapy, expect your red blood cell counts (hemoglobin/hematocrit) to rise and your good cholesterol (HDL) to drop slightly. You will need regular blood tests to monitor these changes. Current large-scale reviews do not show that testosterone increases your risk of heart attacks, strokes, or prostate cancer, but the long-term safety data is still considered low quality due to short study durations.

ModerateQualifiesLOW confidence
Testosterone treatment was associated with a significant increase in hemoglobin [weighted mean difference (WMD), 0.80 g/dl; 95% confidence interval (CI), 0.45 to 1.14] and hematocrit (WMD, 3.18%; 95% CI, 1.35 to 5.01), and a decrease in high-density lipoprotein cholesterol (WMD, -0.49 mg/dl; 95% CI, -0.85 to -0.13). There was no significant effect on mortality, prostate, or cardiovascular outcomes.
Mercè Fernández-Balsells et al. · The Journal of Clinical Endocrinology & Metabolism · 2010

Why this rating

The study is a systematic review and meta-analysis of 51 trials, but the authors explicitly rate the overall quality of evidence as 'low' due to brief follow-up and methodological limitations.

Source

Adverse Effects of Testosterone Therapy in Adult Men: A Systematic Review and Meta-Analysis

Mercè Fernández-Balsells et al. · The Journal of Clinical Endocrinology & Metabolism · 2010

DOI 10.1210/jc.2009-2575

Meta-analysis · 51 studiesCited 717×
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DOI resolved against Crossref · corpus check 2026-06-10

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