Normal CBC Reference Ranges in Healthy Adults
Red Blood Cell Parameters
The most reliable reference intervals for hemoglobin are 13.5–17.5 g/dL for men and 12.0–15.5 g/dL for women, with hematocrit ranges of 41–53% for men and 36–46% for women. 1
- Red blood cell count (RBC) shows significant sex differences, with males having higher values than females at all ages 2, 3
- Mean corpuscular volume (MCV) normal range is 80–100 fL 1
- Hemoglobin is more reliable than hematocrit for clinical assessment because hematocrit can falsely increase by 2–4% with prolonged sample storage, while hemoglobin remains stable 1
- Adult males and post-menopausal females typically have hemoglobin 15.5 ± 2.0 g/dL and hematocrit 47 ± 6%, while menstruating females have hemoglobin 14.0 ± 2.0 g/dL and hematocrit 41 ± 5% 1
White Blood Cell Parameters
White blood cell count reference ranges are not explicitly stated in the highest-quality guidelines, but research studies consistently report ranges of approximately 4,000–11,000 cells/mm³ for adults. 2, 3, 4
- An elevated WBC count (≥14,000 cells/mm³) warrants careful assessment for bacterial infection 1
- Left shift is defined as band neutrophils ≥16% of total WBCs or absolute band count ≥1,500 cells/mm³, indicating significant bacterial infection even when total WBC is normal 1, 5
- Manual differential count is essential for accurately assessing band forms and immature neutrophils, as automated analyzers are insufficient 1, 5
- WBC count is highest in early childhood and decreases with age 3
- Neutrophil count is lowest in early childhood and increases with age, while lymphocyte count peaks in early childhood then decreases 3
Platelet Parameters
Platelet count reference ranges vary by geographic region, with most populations showing ranges of approximately 150,000–400,000/mm³. 1, 2, 4
- Platelet count >400 × 10³/μL is considered elevated and may indicate underlying pathology 1
- Prophylactic platelet transfusion is suggested when counts are <10,000/mm³ in the absence of bleeding, <20,000/mm³ with significant bleeding risk, and ≥50,000/mm³ for active bleeding or invasive procedures 1
- Platelet counts are highest in early childhood and decrease with age 3
- Females have higher platelet counts than males from puberty onwards 3
- Regional variation exists: median platelet counts from certain geographic areas may be significantly lower than others 2
Iron Status Parameters
Normal serum ferritin ranges are 20–250 μg/L in men and 20–200 μg/L in women, with transferrin saturation of 20–50% considered normal. 1
- Serum iron normal range is 50–175 μg/dL 1
- Total iron-binding capacity (TIBC) normal range is 250–370 μg/dL (45–66 μmol/L) 1
- Ferritin levels are affected by inflammation; values may be elevated in inflammatory conditions even with concurrent iron deficiency 1
Important Considerations for Interpretation
Laboratory values must be interpreted in clinical context, as reference ranges vary by age, sex, ethnicity, altitude, and analyzer technology. 1, 2, 3
- Racial/ethnic differences exist: among 38 standard laboratory tests, only five (glucose, phosphorus, potassium, total bilirubin, uric acid) showed no significant racial/ethnic variation 1
- Black participants have significantly higher normal ranges for CPK, globulin, and total protein, but lower ranges for hematocrit, hemoglobin, total cholesterol, triglycerides, and WBC compared to Whites 1
- The lower limit of normal for hemoglobin is 9.6 g/dL in Black women, which falls below eligibility thresholds used in some clinical trials 1
- Altitude increases hemoglobin levels: at 1,000 meters, hemoglobin increases by +0.2 g/dL; at 4,000 meters, by +3.5 g/dL 6
- Age affects multiple parameters: alkaline phosphatase increases by 20% between the 3rd and 8th decade 1
- Individual laboratories should validate reference intervals for their local population and specific analyzer technology 4, 7, 8