What is the normal hematocrit (HCT) range for adults?

Normal Hematocrit Ranges for Adults

The normal hematocrit range for adults varies by sex, with values of 41-50% (average 47%) for adult males/post-menopausal females and 36-46% (average 41%) for menstruating females. 1

Normal Hematocrit Values by Sex and Age

• Adult males/post-menopausal females: 47% ± 6% (range: 41-53%) 1
• Menstruating females: 41% ± 5% (range: 36-46%) 1
• These ranges correspond to hemoglobin values of approximately 15.5 ± 2.0 g/dL for males/post-menopausal females and 14.0 ± 2.0 g/dL for menstruating females 1

Factors Affecting Normal Hematocrit Values

Altitude

• Hematocrit increases with altitude due to increased erythropoietin production 2
• For every 1,000 meters above sea level, hematocrit increases by approximately:
  • At 1,000m: +0.2 g/dL (hemoglobin equivalent)
  • At 2,000m: +0.8 g/dL
  • At 3,000m: +1.9 g/dL
  • At 4,000m: +3.5 g/dL 2

Age

• While some studies previously suggested decreasing hematocrit with aging in men, current guidelines do not recommend adjusting normal ranges for age in adults 2
• Anemia in older adults should not be considered a normal consequence of aging but rather a sign of potential underlying pathology 2

Clinical Significance

• Hematocrit values below the normal range may indicate anemia, which should be investigated when:
  • Hematocrit falls below 37% in adult males/post-menopausal females 2
  • Hematocrit falls below 33% in menstruating females 2

Measurement Considerations

• Hemoglobin is generally preferred over hematocrit for clinical assessment due to:
  • Greater stability when blood samples are stored at room temperature
  • Lower variability across automated analyzers
  • Lack of interference from conditions like hyperglycemia 2, 1
• When hematocrit is measured, samples should be analyzed promptly or refrigerated, as MCV (and thus calculated hematocrit) can increase by 2-4% with prolonged storage 2

Clinical Applications

• In chronic kidney disease management, target hematocrit is 33-36% (corresponding to hemoglobin 11-12 g/dL) 2
• Survival rates improve when hematocrit exceeds 32-33% in patients with chronic kidney disease 2
• For hemodialysis patients, predialysis hematocrit measurements are standard for monitoring anemia 2

Understanding normal hematocrit ranges is essential for proper diagnosis and management of various conditions, particularly anemia and polycythemia, with recognition that these values may need adjustment based on altitude and other physiological factors.