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  • Also Known As:
  • Haemoglobin
  • H&H
  • Hgb
  • Hb
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Test Quick Guide

Hemoglobin is an iron-rich protein found in red blood cells that gives red blood cells their unique red color. It is primarily responsible for carrying oxygen from your lungs to the rest of the cells in the tissues and organs of your body.

A hemoglobin test is often used to detect anemia, which is a deficiency of red blood cells that can have diverse health effects. While hemoglobin can be tested on its own is more often tested as part of a complete blood count (CBC) test that also measures levels of other types of blood cells.

About the Test

Purpose of the test

A hemoglobin test is used to find out how much hemoglobin is in your blood. It is most often used to determine if you have low levels of red blood cells, which is a condition known as anemia.

In addition to identifying anemia, a hemoglobin test can be involved in the diagnosis of other health problems like liver and kidney disease, blood disorders, malnutrition, some kinds of cancer, and heart and lung conditions.

For people who have been treated for anemia or other conditions that can affect hemoglobin levels, a hemoglobin test may be ordered in order to check their response to treatment and monitor the progression of their overall health.

What does the test measure?

A hemoglobin test measures the volume of the protein hemoglobin found in your red blood cells. It is measured in grams per deciliter (g/dL) of blood or grams per liter (g/L) of blood.

Hemoglobin is one component of red blood cells (RBC) and gives these cells their red color. A main function of hemoglobin is to carry oxygen to cells throughout the body. It also has a role in transporting carbon dioxide from the organs and tissues back to the lungs where it can be exhaled.

When measured as part of a complete blood count test, other blood components may be measured including:

  • White blood cells (WBCs), which are involved in immune function
  • Platelets, which enable the blood to clot when needed
  • Hematocrit, which is the proportion of blood made up of red blood cells

When should I get a hemoglobin test?

Hemoglobin is one indicator of how much oxygen your body may be getting. Hemoglobin levels can also reflect whether you have enough iron in your blood. Accordingly, your provider may order a complete blood count to measure hemoglobin if you are experiencing signs and symptoms of low oxygen or low iron. These symptoms can include:

  • Fatigue
  • Shortness of breath during physical activity
  • Dizziness
  • Skin that paler or yellower than usual
  • Headaches
  • Irregular heartbeat

Although less common, high hemoglobin levels can also cause health problems. A hemoglobin test may be ordered if you have signs of abnormally high hemoglobin levels, such as:

  • Disturbed vision
  • Dizziness
  • Headache
  • Slurred speech
  • Reddening of the face

Your provider may also order a hemoglobin test for you if you have been diagnosed with or are suspected of having:

  • Blood disorders like sickle cell disease or thalassemia
  • Diseases affecting the lungs, liver, kidneys, or cardiovascular system
  • Significant bleeding from trauma or surgery
  • Poor nutrition or a diet that is low in vitamins and minerals, specifically iron
  • Significant long-term infection
  • Cognitive impairment, especially in the elderly
  • Certain types of cancer

You most often see results for a hemoglobin test as part of a complete blood count test. A CBC is part of a common collection of tests that are often ordered by a provider to assess your overall health. For this reason, having a hemoglobin test does not necessarily mean that your provider suspects that you have a health problem.

Finding a Hemoglobin Test

How to get tested

A hemoglobin test is most commonly conducted by a licensed professional in a healthcare setting. It is usually part of a complete blood count test that is done in a doctor’s office, clinic, laboratory, or hospital. The test may be performed with a  blood draw or a fingerstick test.

A hemoglobin test is normally prescribed by a doctor, so talk with your health care provider if you have symptoms that could be related to abnormal hemoglobin levels.

Can I take the test at home?

There are options for at-home hemoglobin testing. At home tests use one or more drops of blood to provide an estimation of hemoglobin levels. The drops of blood are obtained by pricking your finger with a tiny needle.

At-home hemoglobin tests may produce values that are less accurate than laboratory testing, especially for certain patients. For the most accurate results, hemoglobin tests should be  administered by trained laboratory personnel.

Your doctor can help you understand if at-home testing is appropriate in your case, and you should never use at-home tests in place of consultation with your doctor about your health.

How much does the test cost?

Hemoglobin tests are usually part of a complete blood count. The cost for a CBC panel depends on whether you have health insurance and whether it covers the test. Other factors that can affect the cost include where your blood is drawn and the charges for the laboratory where your provider sends your blood sample.

Check directly with your doctor or your insurance provider to find out about expected costs, including any copays or deductibles.

Taking a Hemoglobin Test

Hemoglobin is measured by taking a blood sample. A hemoglobin test is most often part of a blood draw ordered and conducted by a medical professional in a healthcare setting.

In infants, hemoglobin tests may be conducted by pricking the heel or finger of the child.

Before the test

Unless specified by your provider, there is no special preparation needed prior to a hemoglobin test. In some instances, hemoglobin is tested along with other blood tests. When you are getting more than one blood test, your provider may ask you to not eat anything for a certain amount of time prior to your test. If you have questions or concerns about any test preparation, contact your healthcare provider for detailed instructions.

During the test

Most hemoglobin tests involve a blood draw from a vein inside your elbow or at the top of your hand. The steps for taking a blood draw include:

  1. The area is cleansed with an antiseptic wipe.
  2. A band, called a tourniquet, is placed around your arm to increase the pressure in your arm and make your vein more visible and easier to access with a needle.
  3. A needle is placed in your vein. A test tube is attached to the needle and is filled with blood. You may feel a pinch or a little pain, which may result in bruising or some bleeding.
  4. If you are getting other blood tests in addition to a hemoglobin test you may have more than one tube of blood drawn.

For young children, testing may involve a blood sample taken from the heel or finger. Those tests follow these steps:

  1. The finger or heel is cleaned with alcohol or an antiseptic wipe.
  2. The finger or heel is stuck with a small needle, resulting in 2-3 drops of blood.
  3. The first drops of blood are wiped away.
  4. As the next drop of blood is produced, a test strip is prepared for analysis.
  5. The blood is applied to the test strip so that it can be analyzed on-site.

After the test

Once blood is drawn, the healthcare provider may apply pressure to the puncture site with a cotton swab. If you are prone to bleeding, they may place a band-aid over the cotton swab to maintain the pressure.

After any blood draw test, such as a hemoglobin test, it’s important to watch out for dizziness or lightheadedness. Your provider may want you to stay seated for a few minutes until they can determine that you are safe to get up and walk and/or drive.

Other than possible lightheadedness, side effects from a blood draw may include slight bruising at the puncture site.

Hemoglobin Test Results

Receiving test results

Results from a hemoglobin test are often available within a few days after you have had your blood drawn. You may receive results by mail or electronically. Your doctor’s office may also contact you to discuss your test results.

Interpreting test results

Hemoglobin results are measured in volume. The numbers associated with your result are in grams per deciliter or g/dL, but the test report may not have “g/dL” listed after the number. For example, your test result may be written as 14 or 14 g/dL.

Normal hemoglobin reference ranges may vary depending on several factors, including age, sex, ethnicity, pregnancy status, genetics, the altitude at which you live, and lifestyle choices.

The high and low values of a normal test result, called the reference range, may differ depending on the laboratory and the methods used to conduct the test. For this reason, it is essential to look at the reference range listed on your test report.

An example of potential reference range, provided by the American Board of Internal Medicine, is listed in the following tables:

While these provide an example of a potential reference range, any person’s results are only considered abnormal based on the range used by the specific laboratory that performed the test.

Because hemoglobin is affected by many factors, it is important that you discuss your results with your provider if you have any concerns about your results. Only your doctor can clarify if your hemoglobin test results are normal for your situation.

If hemoglobin levels are low, it can be a sign of anemia. There are many potential causes of anemia including blood loss, nutritional deficiencies, and many other conditions.

High hemoglobin can also be a sign of underlying health problems including conditions affecting the lung and heart. Dehydration, smoking, living at a high altitude, and some genetic conditions can also lead to high levels of hemoglobin.

Abnormal hemoglobin levels are not a diagnosis of any of these conditions. Instead, your hemoglobin levels are evaluated in the context of your symptoms, other blood counts, and additional test results to diagnose an underlying cause of high or low levels of hemoglobin.

Are test results accurate?

Hemoglobin tests are one of the most essential and fundamental blood tests conducted during medical assessments. The test is commonly used and relied upon in various health care settings.

No test is perfect, though, and your hemoglobin result may be affected by things that don’t necessarily indicate a health problem. For example, results may not accurately reflect healthy hemoglobin levels in pregnant people, people who are dehydrated, and people who live at higher elevations.

Do I need follow-up tests?

Abnormal hemoglobin test results may or may not require follow-up testing. Hemoglobin is often evaluated alongside other components of a complete blood count to look for signs of disease or monitor health conditions.

If they feel it is necessary, your doctor may order additional testing if you have low hemoglobin. Often follow-up testing aims to evaluate the cause or causes of anemia. Testing for anemia may include tests such as a reticulocyte count, a renal panel, a liver panel, hemolysis testing, or a blood smear.

Follow-up testing is based on your symptoms, medical history, and the results of other tests. For questions about follow-up testing, make sure to speak with your doctor.

Questions for your doctor about test results

The following questions may be helpful when reviewing your hemoglobin test results with your doctor:

  • Was my hemoglobin level abnormal?
  • If it was abnormal, do you consider that level to be concerning in my case?
  • Are abnormal hemoglobin levels something I can change?
  • Do I need to monitor my hemoglobin levels at home?
  • Based on my hemoglobin levels, is there any other testing that is needed?


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