What are the normal hemoglobin levels by age and sex to diagnose anemia?

Normal Hemoglobin Levels by Age and Sex for Diagnosing Anemia

Anemia is defined as hemoglobin levels <13.5 g/dL in adult males and <12.0 g/dL in adult females, regardless of age. 1

Normal Hemoglobin Ranges by Age and Sex

Adult Males (≥15 years)

• Normal range: 13.5-17.5 g/dL 1
• No downward adjustment recommended for older males despite lower mean values in elderly 1

Adult Females (≥15 years)

• Normal range: 12.0-15.5 g/dL 1
• No adjustment needed for postmenopausal status 1

Children and Adolescents

• 1-2 years: 11.0-13.0 g/dL (both sexes) 1
• 3-5 years: 11.5-13.5 g/dL (both sexes) 1
• 6-8 years: 11.5-13.5 g/dL (both sexes) 1
• 9-11 years:
  • Girls: 11.9-14.0 g/dL 1
  • Boys: 12.0-14.5 g/dL 1
• 12-14 years:
  • Girls: 11.7-14.5 g/dL 1
  • Boys: 12.4-15.5 g/dL 1

Factors Affecting Hemoglobin Levels

Altitude Adjustment

• Hemoglobin increases with altitude due to physiological adaptation 1, 2
• Adjustments to normal ranges should be made for patients living at elevations >1,000 meters:
  • At 1,000 meters: +0.2 g/dL 1
  • At 1,500 meters: +0.5 g/dL 1, 2
  • At 2,000 meters: +0.8 g/dL 1, 2
  • At 2,500 meters: +1.3 g/dL 1
  • At 3,000 meters: +1.9 g/dL 1

Race/Ethnicity Considerations

• African Americans typically have hemoglobin levels 0.5-1.0 g/dL lower than Caucasians 1
• Mexican Americans show slightly different normal ranges compared to non-Hispanic whites 1

Other Factors

• Smoking increases hemoglobin levels by 0.3-1.0 g/dL 1, 3
• Pregnancy decreases hemoglobin (separate guidelines apply) 1
• Chronic diseases may affect hemoglobin levels independently of iron status 1, 4

Severity Classification of Anemia

• Mild anemia:

  • Men: 11.0-13.4 g/dL
  • Women: 11.0-11.9 g/dL 3

• Moderate anemia:

  • Both sexes: 8.0-10.9 g/dL 3

• Severe anemia:

  • Both sexes: <8.0 g/dL 3

Important Clinical Considerations

• Anemia prevalence increases with age, reaching up to 41% in men and 21% in women aged ≥90 years 5
• Plasma volume expansion can cause "dilutional anemia" without true hemoglobin mass deficiency, particularly in heart failure and liver disease 4
• The WHO definition (Hb <13.0 g/dL for men, <12.0 g/dL for women) is slightly different from the clinical practice guidelines cited above 6
• Anemia should not be considered a normal consequence of aging and warrants appropriate clinical investigation 5

Remember that these values represent population norms, and individual patient factors should be considered when interpreting hemoglobin results and diagnosing anemia 1, 6.