Management of Testosterone‑Induced Erythrocytosis in Adult Men

Incidence & Risk Factors

Testosterone therapy causes erythrocytosis in 15–44 % of treated men, with injectable formulations carrying the highest risk. 1
Low SHBG increases free testosterone availability, further raising erythrocytosis risk. 1
Elevated estradiol (39 pg/mL; reference ≤ 29) is linked to a higher likelihood of erythrocytosis. 1

Hemoglobin 18.8 g/dL (reference 13.0–17.5) and hematocrit 53.7 % (reference 38.0–50.0) indicate significant erythrocytosis. 2
Hematocrit > 52 % increases blood viscosity and can aggravate coronary, cerebrovascular, or peripheral vascular disease. 2
Iron deficiency (ferritin 21 ng/mL; reference 24–336) may mask or exacerbate testosterone‑induced erythrocytosis. 1
Low SHBG (10.5 nmol/L; reference 13.3–89.5) contributes to supraphysiologic free testosterone levels. 1

Temporarily discontinue testosterone until hematocrit falls below 50 %. 3
Therapeutic phlebotomy is recommended if hematocrit remains > 54 % or if the patient has cardiovascular risk factors. [1][2]
Dose reduction by 25–50 % when testosterone therapy is resumed. 3
Monitoring schedule: check hemoglobin/hematocrit every 3 months initially, then every 6 months. [3][4]

Aim for mid‑normal total testosterone (400–600 ng/dL) with normal free testosterone levels. 3
Switching from injectable to transdermal formulations markedly lowers erythrocytosis rates (injectable ≈ 43.8 % vs. transdermal ≈ 2.8–15.4 %).

Formulation	Erythrocytosis Rate
Injectable	43.8 %
Transdermal	2.8–15.4 %

Iron supplementation should be deferred until hematocrit is controlled, as repletion may further raise hematocrit. [1][2]
Evaluate the source of iron deficiency (e.g., gastrointestinal loss, dietary insufficiency). 2
Low morning cortisol (5.9 µg/dL) warrants an ACTH stimulation test to rule out adrenal insufficiency. 5

Statin therapy is indicated for dyslipidemia (LDL 122 mg/dL, HDL 31 mg/dL, Chol/HDL 5.7) to mitigate cardiovascular risk. 3
Counsel on lifestyle modifications (diet, exercise, weight management). 5
Blood pressure should be monitored regularly. 2

Every 3–6 months (first year): hemoglobin/hematocrit, total & free testosterone, PSA, digital rectal exam, lipid panel, blood pressure. [3][4]
Annually thereafter: repeat the above assessments; consider prostate biopsy if PSA rises > 1.0 ng/mL within 6 months or > 0.4 ng/mL/year thereafter. 4
Screen for sleep‑apnea symptoms at each visit. 2

Do not ignore elevated hematocrit; it is the most common serious complication requiring intervention. [1][2]
Do not supplement iron until erythrocytosis is adequately controlled. 1
Do not overlook low cortisol; adrenal function assessment is essential. 5
Do not assume cardiovascular safety of testosterone therapy; long‑term data are limited and patients may have existing risk factors. [6][5]

A hemoglobin level of ≈ 18 g/dL (corresponding to a hematocrit ≈ 55%) is considered clinically significant erythrocytosis that warrants therapeutic intervention. Endocrine Society 7

Erythrocytosis is the most common serious adverse event reported in testosterone therapy trials, with a higher incidence observed in older men. Endocrine Society 7

The Endocrine Society recommends withholding testosterone until the hematocrit falls below 50% (approximately hemoglobin < 17.5 g/dL) before considering re‑initiation. 7

Consensus guidelines set a hematocrit ≥ 54% as the trigger for therapeutic phlebotomy, although many clinicians intervene at lower thresholds (50–52%) in patients with cardiovascular risk factors. Endocrine Society 7

Data from the TRAVERSE trial and pooled meta‑analyses show that, when hematocrit is appropriately monitored and managed, testosterone therapy does not significantly increase the incidence of major adverse cardiovascular events. Endocrine Society 7