Lab Test: Hemoglobin, Hgb Level
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.
- 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
- 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
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.
- 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.
- 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
- Antibiotics, antieoplastic drugs, aspirin, indomethacin (Indocin), rifampin, and sulfonamides.
- 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.
- Explain the procedure to the patient.
- Tell the patient that no fasting is required.
What To Tell Patient Before & After
MESH Terms & Keywords