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Hemoglobin

Hgb; Hb; Anemia - Hb; Polycythemia - Hb

Hemoglobin is a protein in red blood cells that carries oxygen. The hemoglobin test measures how much hemoglobin is in your blood.

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Hemoglobin

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How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

No special preparation is necessary.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

The hemoglobin test is a common test and is almost always done as part of a complete blood count (CBC). Reasons or conditions for ordering the hemoglobin test include:

Normal Results

Normal results for adults vary, but in general are:

Normal results for children vary, but in general are:

The ranges above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your health care provider about the meaning of your specific test results.

What Abnormal Results Mean

LOWER THAN NORMAL HEMOGLOBIN

Low hemoglobin level may be due to:

HIGHER THAN NORMAL HEMOGLOBIN

High hemoglobin level is most often caused by low oxygen levels in the blood (hypoxia), present over a long period of time. Common reasons include:

Other reasons for high hemoglobin level includes:

Risks

There is little risk involved with having your blood taken.Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight, but may include:

Related Information

CBC blood test
Hemoglobin electrophoresis
Anemia
Erythropoietin test
Hemolysis
Hemolytic transfusion reaction
Bleeding
Lead poisoning
Malnutrition
Folic acid in diet
Vitamin B12
Vitamin B6
Cor pulmonale
Idiopathic pulmonary fibrosis
Polycythemia vera
Anemia of chronic disease
Hemoglobin C disease
Diabetes
Giant cell arteritis
Glucose-6-phosphate dehydrogenase deficiency
Type 1 diabetes
Aplastic anemia
Immune hemolytic anemia
Iron deficiency anemia
Paroxysmal cold hemoglobinuria (PCH)
Paroxysmal nocturnal hemoglobinuria (PNH)
Pernicious anemia
Placenta abruption - definition
Polymyalgia rheumatica
Rhabdomyolysis
Drug-induced immune hemolytic anemia

References

Bunn HF. Approach to the anemias In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 158.

Chernecky CC, Berger BJ. Hemoglobin (HB, Hgb). In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. Philadelphia, PA: Elsevier; 2013:621-623.

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Review Date: 2/18/2018  

Reviewed By: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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