What does hemoglobin measure and why does it matter?
Hemoglobin is the oxygen-carrying protein in red blood cells. Low values cause anemia and fatigue; high values on TRT signal erythrocytosis, which raises cardiovascular risk and requires dose adjustment.
Full answer
Hemoglobin is the iron-containing protein that transports oxygen from lungs to tissues. It anchors the CBC and is the most actionable marker in anemia workup. Low hemoglobin causes fatigue, exercise intolerance, cognitive slowing, and shortness of breath. High hemoglobin — particularly relevant in men on TRT — signals erythrocytosis, the most common testosterone-therapy side effect requiring intervention. oMeds provider review halts TRT dose escalation when hematocrit approaches 52% and triggers therapeutic phlebotomy at 54%. Hemoglobin is required at baseline and on recalibration cadence in all Hormone Optimization patients. In women, low hemoglobin most commonly reflects iron deficiency from menstrual loss.
Educational. Not a substitute for individualized provider review.
- Hemoglobin — Primary source · oMeds
- Reviewed by Dr. Laura Purdy, MD, MBA · Clinical Director, oMeds · Last reviewed 2026-05-29