Hematocrit
Hematocrit measures the proportion of blood volume occupied by red blood cells. Males have higher values than females across all adult age groups.
Unit: % · 12 slices · age and sex · 1 source
Filed under panels: Complete Blood Count · topics: Hematology
Hematocrit is the fraction of blood volume occupied by red blood cells, expressed as a percentage. It closely tracks hemoglobin and is influenced by the same factors: testosterone-driven erythropoiesis, menstrual losses, hydration status, and age-related changes in red cell production.
Population Distribution
Browse by Demographic
| Age (years) | male (%) | female (%) |
|---|---|---|
| 20-29 | 40–49.2 (44.8) | 35.2–43.8 (39.9) |
| 30-39 | 40.2–49.8 (44.5) | 34.4–44.1 (39.6) |
| 40-49 | 39.9–49.3 (44.5) | 32.7–44.3 (40) |
| 50-59 | 39.4–49.4 (44.7) | 35.1–45.4 (40.6) |
| 60-69 | 37–50.1 (44) | 35.1–45.7 (40.6) |
| 70+ | 35.1–49.1 (42.7) | 34.3–45.9 (40.1) |
Frequently Asked Questions
How is hematocrit related to hemoglobin?
Both reflect red cell mass. Hematocrit is the volume fraction of red cells, while hemoglobin measures oxygen-carrying protein concentration. They are strongly correlated and rise or fall together in most conditions.
Can dehydration affect hematocrit?
Yes. Dehydration reduces plasma volume, which concentrates red cells and raises hematocrit without any change in actual red cell mass. Population percentiles reflect typical hydration states at the time of measurement.
Why do males have higher hematocrit than females?
Testosterone stimulates erythropoietin production, driving greater red blood cell output. Females also experience regular menstrual blood loss, which reduces red cell mass. Both factors together produce a consistent and substantial sex difference across all adult age groups.