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Hemoglobin

Alternative Names: Hgb; Hb

Hemoglobin is a protein in red blood cells that carries oxygen. A blood test can tell how much hemoglobin you have in your blood.

See also: Hemoglobin electrophoresis

Why is the Test Performed?

The hemoglobin test is almost always done as part of acomplete blood count (CBC).

How is the Test Performed?

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

Preparation for the Test

No special preparation is necessary.

How will the Test Feel?

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Hemoglobin Risks

Veins and arteries vary in size from one patient 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:

  • Excessive bleeding
  • Fainting or feeling light-headed
  • Hematoma (blood accumulating under the skin)
  • Infection (a slight risk any time the skin is broken)

Normal Results for Hemoglobin

Normal results vary, but in general are:

  • Male: 13.8 to 17.2 gm/dL
  • Female: 12.1 to 15.1 gm/dL

Note: gm/dL = grams per deciliter

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What Abnormal Results Mean

Lower-than-normal hemoglobin may be due to:

Higher-than-normal hemoglobin may be due to:

Additional conditions under which the test may be performed:

Related Images

Learn more about Hemoglobin

Review Date: 2/9/2010
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
Do not use this information for medical emergencies - Call 911. This information should not be used for the diagnosis or treatment of any medical condition. A licensed medical practitioner should always be consulted for diagnosis and treatment of any and all medical conditions. Links to other websites do not constitute endorsements and are provided for information only. Any duplication or distribution of this information is strictly prohibited.
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