Hemoglobin (HGB)
Oxygen-carrying iron-containing protein in red blood cells. Tracks hematocrit closely; a primary TRT safety marker.
TL;DR. Normal adult male: ~13.5-17.5 g/dL. On TRT: ~15-17 is common; ≥18 g/dL is the practical companion threshold to HCT ≥54% and triggers the same workup. HGB and HCT always move together,
HCT% ≈ 3 × HGB (g/dL) with normal-shaped cells.
Definition
Hemoglobin is the iron-containing metalloprotein inside red blood cells that binds and transports oxygen from lungs to tissue, and returns CO₂ to the lungs. It is reported in grams per deciliter. Hemoglobin and hematocrit track closely because they measure the same underlying red-cell mass from two angles.
Reference range
| Population | HGB (g/dL) |
|---|---|
| Adult male (non-TRT) | 13.5-17.5 |
| Adult male on TRT (typical) | 15-17 |
| Adult female | 12.0-15.5 |
| TRT safety threshold (approx) | ≥18 |
| Mild anemia | 10-13 |
| Severe anemia | <8 |
Units: g/dL × 10 = g/L. Ranges are laboratory-, age-, and altitude-dependent.
What high HGB means
- TRT or anabolic-androgen use, expected, monitored.
- Dehydration, most common cause of a spuriously high result.
- Obstructive sleep apnea, nocturnal hypoxia.
- Heavy smoking, COPD, high-altitude residence.
- Polycythemia vera, JAK2-mutation-driven.
What low HGB means
- Iron deficiency, usually microcytic; ferritin is the next test.
- B12 / folate deficiency, usually macrocytic; check MCV.
- Chronic kidney disease, chronic inflammation, anemia of chronic disease.
- Blood loss: acute GI bleed, occult GI bleed, heavy menses.
- Hemolysis, autoimmune, mechanical, hereditary.
- Bone-marrow suppression, chemotherapy, some drugs.
When to test
- Always on the CBC, tested automatically alongside HCT.
- Baseline and follow-up on TRT.
- Any fatigue, exercise intolerance, tachycardia, pallor, black stools.
Related tests
FAQ
- What is the normal hemoglobin range?
- Approximately 13.5-17.5 g/dL for adult men and 12.0-15.5 g/dL for adult women. On TRT, many men run 15-17 g/dL; values ≥18 g/dL usually coincide with hematocrit ≥54% and warrant the same management as high HCT (hydration check, sleep-apnea workup, smaller more frequent doses, possible phlebotomy).
- How is hemoglobin related to hematocrit?
- They are highly correlated, in most normal-shaped red cells the ratio is approximately HCT% ≈ 3 × HGB (g/dL). So HGB 15 g/dL roughly corresponds to HCT 45%. If the ratio diverges sharply, suspect a red-cell-size abnormality: macrocytic anemia (B12, folate, alcohol), microcytic anemia (iron deficiency, thalassemia), or a lab artifact.
- What does high hemoglobin mean?
- Same causes as high hematocrit: TRT or anabolic use, dehydration, obstructive sleep apnea, chronic hypoxia from lung disease or altitude, heavy smoking, and polycythemia vera. High HGB increases blood viscosity and in extreme values raises thromboembolic risk.
- What does low hemoglobin mean?
- Low HGB = anemia. Common causes: iron deficiency (microcytic, worldwide most common), B12/folate deficiency (macrocytic), chronic kidney disease, anemia of chronic disease, blood loss (GI bleed, heavy menses), and hemolysis. Symptoms: fatigue, exercise intolerance, tachycardia, pallor. Severity is defined by HGB: mild 10-13, moderate 8-10, severe under 8 g/dL.
- Should I track HGB or HCT on TRT?
- Track both, they come on the same CBC and move together. Most TRT-safety guidelines cite HCT ≥54% as the actionable threshold; HGB ≥18 g/dL is the practical companion. VitaLog's CBC tracker flags both independently and alerts when either crosses the watchlist or out-of-range boundary.