Why is hgb test done

Other names: Hb, Hgb. What is it used for? Hemoglobin tests are also frequently performed with other tests, such as: Hematocrit, which measures the percentage of red blood cells in your blood Complete blood count , which measures the number and type of cells in your blood. Why do I need a hemoglobin test? Your health care provider may have ordered the test as part of a routine exam, or if you have: Symptoms of anemia, which include weakness, dizziness, pale skin, and cold hands and feet A family history of thalassemia , sickle cell anemia , or other inherited blood disorder A diet low in iron and minerals A long-term infection Excessive blood loss from an injury or surgical procedure.

What happens during a hemoglobin test? Will I need to do anything to prepare for the test? Are there any risks to the test? What do the results mean? There are many reasons your hemoglobin levels may be outside the normal range. Low hemoglobin levels may be a sign of: Different types of anemia Thalassemia Iron deficiency Liver disease Cancer and other diseases High hemoglobin levels may be a sign of: Lung disease Heart disease Polycythemia vera, a disorder in which your body makes too many red blood cells.

It can cause headaches, fatigue, and shortness of breath. Is there anything else I need to know about a hemoglobin test? References Aruch D, Mascarenhas J. Contemporary approach to essential thrombocythemia and polycythemia vera. Current Opinion in Hematology [Internet]. For a hemoglobin test, a member of your health care team takes a sample of blood by pricking your fingertip or inserting a needle into a vein in your arm.

For infants, the sample may be obtained by pricking the heel. The blood sample is sent to a lab for analysis. You can return to your usual activities immediately after the sample is taken. Normal ranges for children vary with age and sex.

The range for a normal hemoglobin level may differ from one medical practice to another. If your hemoglobin level is lower than normal, you have anemia. There are many forms of anemia, each with different causes, which can include:.

If you've been previously diagnosed with anemia, a hemoglobin level that's lower than normal may indicate a need to alter your treatment plan. If you've been previously diagnosed with polycythemia vera, an elevated hemoglobin level may indicate a need to alter your treatment plan. If your hemoglobin level is below or above normal, your doctor may want to evaluate the hemoglobin test results along with those of other tests, or additional tests may be necessary, to determine next steps.

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Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. If you have questions about the hemoglobin test or what the results of the test mean, speak with your doctor.

Reviewed by: Larissa Hirsch, MD. Larger text size Large text size Regular text size. What Is a Blood Test? What Is a Hemoglobin Test?