Red Blood Cell Count (RBC)
Red blood cell count measures the number of erythrocytes per unit volume of blood. Males maintain higher counts than females throughout adulthood, with a gradual decline in both sexes after age 60.
Unit: million cells/uL · 12 slices · age and sex · 1 source
Filed under panels: Complete Blood Count · topics: Hematology
The red blood cell count reflects the number of circulating erythrocytes. It is influenced by erythropoietin production, iron availability, and bone marrow function. RBC count is interpreted alongside hemoglobin, hematocrit, and red cell indices (MCV, MCH, MCHC) to characterize red cell mass and morphology.
Population Distribution
Browse by Demographic
| Age (years) | male (million cells/uL) | female (million cells/uL) |
|---|---|---|
| 20-29 | 4.5–5.7 (5.1) | 4–5.1 (4.5) |
| 30-39 | 4.4–5.7 (5.1) | 3.9–5 (4.5) |
| 40-49 | 4.5–5.7 (5) | 3.9–5 (4.5) |
| 50-59 | 4.4–5.7 (5) | 4.1–5.2 (4.6) |
| 60-69 | 4.1–5.6 (4.9) | 3.9–5.2 (4.5) |
| 70+ | 3.9–5.5 (4.7) | 3.7–5.2 (4.4) |
Frequently Asked Questions
How does RBC count relate to hemoglobin?
Both reflect red cell mass, but they can diverge. A person can have a normal RBC count with low hemoglobin per cell (as in iron deficiency), or fewer red cells that are each larger and carry more hemoglobin. The red cell indices (MCV, MCH) help distinguish these patterns.
Why does RBC count decline with age?
Age-related declines in erythropoietin production (due to reduced kidney function) and increased prevalence of chronic conditions that suppress erythropoiesis both contribute to lower red cell counts in older adults.
Why do males have higher RBC counts than females?
Testosterone stimulates erythropoietin production, increasing red blood cell output from the bone marrow. Females experience regular menstrual blood loss, which reduces circulating red cell mass. Both factors contribute to the consistent male-female gap seen across all adult age groups.