What is hematocrit?
Hematocrit is the percentage of blood volume made up of red blood cells, measured as part of routine blood work to monitor for erythrocytosis during testosterone replacement therapy.
Hematocrit refers to the proportion of red blood cells in your total blood volume, expressed as a percentage. A blood test measures this ratio to determine whether your red blood cell count is within the normal range, typically 38.8 to 50 percent for men.
During testosterone replacement therapy, hematocrit becomes an important marker because testosterone stimulates the bone marrow to produce more red blood cells. This effect, called erythrocytosis, can cause hematocrit levels to rise above normal ranges. Elevated hematocrit thickens the blood, which increases the risk of clotting, stroke, and heart problems.
TRT providers track hematocrit regularly through blood work to catch this early. If levels climb too high, doctors may reduce the testosterone dose, adjust the injection schedule, or recommend blood donation to bring values back down. Some patients require more frequent monitoring than others based on age, dose, and individual response to therapy.
Any provider offering testosterone replacement therapy should include hematocrit checks as part of ongoing care and discuss the results with you at each visit.