Hemoglobin Test
A hemoglobin test measures the levels of an iron-rich protein in your red blood cells to help diagnose blood disorders like anemia.
What is a Hemoglobin Test?
A hemoglobin test measures the levels of hemoglobin in your blood. Hemoglobin is an iron-rich protein in your red blood cells that carries oxygen from your lungs to the rest of your body. Your cells need oxygen to grow, reproduce, and make energy for you to function. Your hemoglobin levels provide information about the health of your red blood cells. If your hemoglobin levels are abnormal, it may be a sign that you have a blood disorder.
Other names: Hb, Hgb, H&H
What is it used for?
A hemoglobin test is a blood test often used to check for anemia, a condition in which your body does not make enough healthy red blood cells. Hemoglobin levels are usually measured as part of a complete blood count (CBC), which is a group of tests that measure the number and type of cells in your blood.
Note: A hemoglobin test is not the same as a hemoglobin A1C test, which is used to check your average blood glucose (blood sugar).
Why do I need a hemoglobin test?
Your health care provider may order the test as part of a routine exam, or if you have:
- Symptoms of anemia, which include weakness, dizziness, and cold hands and feet
- A family history of thalassemia, sickle cell anemia, or other inherited blood disorder
- A diet low in iron and other minerals
- A long-term infection
- Excessive blood loss from an injury or surgical procedure
You may also need this test to monitor the treatment of anemia or other health conditions that could affect your hemoglobin level.
What happens during a hemoglobin test?
A health care professional will take a blood sample from a vein in your arm using a small needle. A small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Will I need to do anything to prepare for the test?
You don't need any special preparation for a hemoglobin test. If your provider has ordered other blood tests, you may need to fast (not eat or drink) for several hours before the test. Your provider will let you know if there are any special instructions.
Are there any risks to the test?
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
What do the results mean?
Your results will compare your hemoglobin level to the normal range, or reference range. This range may vary based on the laboratory used and your age, race, and sex. Knowing how high or low your hemoglobin level is can help your provider determine the severity of your condition.
Low hemoglobin levels may be a sign of:
- Different types of anemia
- Thalassemia
- Iron deficiency
- Liver disease
- Cancer and other diseases
- Blood loss from injury, a heavy menstrual period, or other problems
- Lack of certain nutrients, such as iron or vitamin B-12
High hemoglobin levels may be a sign of:
- Lung disease
- Heart disease
- Polycythemia vera, a disease which causes your bone marrow to make too many red blood cells
- Sleep apnea, a disorder that causes you to repeatedly stop breathing during sleep
Other factors that can affect your results include living at a higher altitude, diet, activity level, certain medicines, dehydration, and smoking.