EBM Consult

Lab Test: Hemoglobin, Hgb Level

    Lab Test
    • Hemoglobin (Hgb)
    • Measurement of hemoglobin in whole blood for the evaluation of the oxygen carrying capacity and management of red blood cell disorders. 
    • The hemoglobin (Hgb) concentration is a measure of the total amount of Hgb in the peripheral blood and serves as a vehicle for oxygen and carbon dioxide transport as well as an important component of the acid-base buffer system. 
    Reference Range
    • Adult males:  13.5-17.5 g/dL (8.4-10.9 mmol/L)
    • Adult females:  12-16 g/dL (7.4-9.9 mmol/L)
    • Pregnant females:  15% below the nonpregnant value
    • Child/adolescent:
      • Newborn:  14-24 g/dL
      • 0-2 weeks:  12-20 g/dL
      • 2-6 months:  10-17 g/dL
      • 6 months- 1 year:  9.5-14 g/dL
      • 1-6 years:  9.5-14 g/dL
      • 6-18 years:  10-15.5 g/dL
    • Critical Values:  <7 g/dL or >21 g/dL
    Clinical Application
    • Normal Hgb values vary according to gender and age, but closely reflects the Hct and RBC values.
      • Note: The Hct in percentage points usually is approximately three tines the Hgb concentration in grams per deciliter when RBCs are of normal size and contain normal amounts of Hgb.
    • Abnormal values indicate the same pathologic states as abnormal RBC counts and Hct concentrations.  Changes in plasma volume are more accurately reflected by the Hgb concentration. 
    • Increased levels may indicate:
      • Erythrocytosis, congenital heart disease, severe chronic obstructive pulmonary disease, polycythemia vera, or severe dehydration (e.g., severe diarrhea, burns). 
    • Decreased levels may indicate:
      • Anemia, hemoglobinopathy, cirrhosis, hemolytic anemia (e.g., erythroblastosis fetalis, hemoglobinopathies, drug-induced hemolytic anemias, transfusion reactions, or paroxysmal nocturnal hemoglobinuria), hemorrhage, dietary deficiency, bone marrow failure, prosthetic valves, renal disease, normal pregnancy, rheumatoid/collagen-vascular diseases, lymphoma, multiple myeloma, neoplasia, leukemia, Hodgkin disease, or splenomegaly.
    Related Tests
    • Hematocrit - this is a measurement of the percentage of the total blood volume taken up the RBCs.
    • Red blood cell count - this is a measurement of the number of RBCs per cubic millimeter of blood.
    • Red blood cell indices - these provide data about the size and Hgb content of the RBC.
    Drug-Lab Interactions
    • Heavy smokers have higher Hgb levels than nonsmokers.
    • Living in high altitudes causes increased Hgb values as a result of a physiologic response to the decreased oxygen available at these high altitudes. 
    • Results increased in vigorous exercise or excitement as well as hemoconcentration (dehydration, burns, severe vomiting, intestinal obstruction). 
    • Drugs that may cause increased levels include: 
      • Gentamicin and methyldopa (Aldomet).
    • Drugs that nay cause decreased levels include: 
      • Antibiotics, antieoplastic drugs, aspirin, indomethacin (Indocin), rifampin, and sulfonamides.
    Test Tube Needed
    • Lavender top tube
    • Collect a venous blood sample.
    • Avoid hemolysis.
    • List on the laboratory slip any drugs that may affect test results.
    • Apply pressure or a pressure dressing to the venipuncture site and observe the site for bleeding.
    Storage and Handling
    • Store specimen at 23°C for 24 hours or at 4°C for 48 hours.
    What To Tell Patient Before & After
    • Explain the procedure to the patient.
    • Tell the patient that no fasting is required.
    • LaGow B et al., eds. PDR Lab Advisor. A Comprehensive Point-of-Care Guide for Over 600 Lab Tests.  First ed. Montvale, NJ: Thomson PDR; 2007.
    • Pagana K, Pagana TJ eds. Mosby's Manual of Diagnostic and Laboratory Tests. 5th Ed.  St. Louis, Missouri. 2014.

MESH Terms & Keywords

  • Hemoglobin, Hgb Level