Does this test have other names?
Hb, Hgb, H and H, Hemoglobin and hematocrit
What is this test?
This is a blood test to find out how much hemoglobin is in your blood. Hemoglobin
is the main part of your red blood cells. Hemoglobin is made up of a protein called
globin and a compound called heme. Heme consists of iron and a pigment called porphyrin,
which gives your blood its red color.
Hemoglobin serves the important role of carrying oxygen and carbon dioxide through
your blood. If your hemoglobin is too low, you may not be able to supply the cells
in your body with the oxygen they need to survive.
Why do I need this test?
You may need this test if it is part of routine blood testing. You may also need to
have your hemoglobin checked if you have anemia or symptoms of anemia. Anemia can
be caused by blood loss, decreased production of red blood cells, or increased destruction
of red blood cells. Your healthcare provider can use your hemoglobin test to help
find the cause of your anemia. These are other reasons you may need this test:
To diagnose a disease that causes anemia
To see how severe your anemia is
To see whether your anemia is responding to treatment
To evaluate a disease called polycythemia
Symptoms of anemia may include:
Shortness of breath
Cold, pale skin
Polycythemia is a disease that causes your body to make too many red blood cells.
Polycythemia may cause:
What other tests might I have along with this test?
Hemoglobin is usually tested as part of a complete blood count, or CBC. A CBC is a
blood test that counts all the different cells in your blood. A hemoglobin test may
also be paired with a hematocrit test. When the two are tested together it is often
called an H and H. The hematocrit blood test tells what percent of your blood is made
up by red blood cells.
What do my test results mean?
Test results may vary depending on your age, gender, health history, the method used
for the test, and other things. Your test results may not mean you have a problem.
Ask your healthcare provider what your test results mean for you.
Hemoglobin measurement is given in grams per deciliter (g/dL). Normal hemoglobin is
different for men, women, and children. Here are the approximate normal values:
High hemoglobin levels can be caused by polycythemia, heart failure, and chronic obstructive
pulmonary disease. Low hemoglobin may be caused by:
How is this test done?
The test is done with a blood sample. A needle is used to draw blood from a vein in
your arm or hand.
Does this test pose any risks?
Having a blood test with a needle carries some risks. These include bleeding, infection,
bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may
feel a slight sting or pain. Afterward, the site may be sore.
What might affect my test results?
Your hemoglobin may be affected by several factors:
Living at high altitudes may make hemoglobin go up.
Certain medicines can make hemoglobin go down or up.
An extreme amount of exercise can make hemoglobin go up.
Pregnancy may make hemoglobin go down.
Taking in too much fluid can make hemoglobin go down.
How do I get ready for this test?
You don't need to prepare for this test. Make sure to tell your healthcare provider
Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements
you are taking. This includes medicines that don't need a prescription and any illicit
drugs you may use.