Serum Hemoglobin Test

What Is a Serum Hemoglobin Test?

A serum hemoglobin test measures the amount of freely moving hemoglobin in your blood serum. Serum is the yellowish fluid that is devoid of blood cells and clotting factors. Hemoglobin is a type of protein which carries oxygen to the tissues.

Normally, all of the hemoglobin in your body is present in your red blood cells. Although, some conditions may lead to some of the hemoglobin to be in your serum. This is known as free hemoglobin. The serum hemoglobin test measures this free hemoglobin.

Doctors often use this test to diagnose or monitor abnormal breakdown of red blood cells. If you have had a recent blood transfusion, this test can monitor for a transfusion reaction. Another cause might be hemolytic anemia. If you have this type of anemia, your red blood cells break down too rapidly. This leads to higher levels of free hemoglobin in your blood.

The test is sometimes reffered as a blood hemoglobin test.

Why Is a Serum Hemoglobin Test Ordered?

Your doctor may order a serum hemoglobin test if you are revealing symptoms of hemolytic anemia. This condition occurs when your red blood cells break down quickly and your bone marrow can’t replace them fast enough.

Your doctor may also perform this test if you have already been diagnosed with hemolytic anemia. In this case, the test can help your doctor monitor your condition.

What Is Hemolytic Anemia?

There are two types of hemolytic anemia.

Extrinsic hemolytic anemia

If you have extrinsic hemolytic anemia, your body produces normal red blood cells. Though, they are destroyed too rapidly because of an infection, an autoimmune disorder, or a specific type of cancer.

Intrinsic hemolytic anemia

If you have intrinsic hemolytic anemia, your red blood cells themselves are defective and their breakdown occurs very rapidly. Sickle cell anemiathalassemiacongenital spherocytic anemia, and G6PD deficiency are all conditions that can cause hemolytic anemia.

Both types of hemolytic anemia cause the similar types of symptoms. Though, you may have additional symptoms if your anemia is caused by an underlying condition.

In the early stages of hemolytic anemia, you may experience:

  • weakness
  • dizziness
  • confusion
  • irritation
  • tiredness

You may also experience headaches.

As the condition develops, your symptoms will become more severe. Your skin may become yellow or pale, and the sclera of your eyes may become blue or yellow. Other symptoms may include:

  • brittle nails
  • heart problems (an increased heart rate or heart murmur)
  • dark colored urine
  • an enlarged spleen
  • an enlarged liver
  • soreness in tongue

How Is the Test Administered?

A serum hemoglobin test needs a small sample of blood to be drawn from your hand or your arm. This process Generally only takes a few minutes:

  1. Your healthcare provider will apply an antiseptic to the area where your blood will be taken.
  2. An elastic band will be tied around your upper arm to increase the amount of blood flow to the veins, causing them to swell. This makes it easier to find a vein.
  3. Then, a needle will be inserted into your vein. After the vein is punctured, the blood will flow through the needle into a small tube that’s attached to it. You may feel little prick when the needle is inserted, but the test itself isn’t painful.
  4. Once needed blood is collected, the needle will be removed and a sterile bandage will be applied over the injection site.

Collected blood is then sent to a lab for testing.

Serum Hemoglobin Test Results

Normal Results

Serum hemoglobin is measured in grams of hemoglobin per deciliter of blood (mg/dL). Lab results differ so your doctor will help recognize if your results are normal or not. If your results come back normal, your doctor may want to perform further testing.

Abnormal Results

High levels of hemoglobin in your serum are normally a sign of hemolytic anemia. Conditions that can lead to abnormal breakdown of red blood cells include, but are not limited to:

  • sickle cell anemia: a genetic disorder that leads your red blood cells to be hard and abnormally shaped
  • G6PD deficiency: when your body does not produce required amount of the enzyme that produces red blood cells)
  • hemoglobin C disease: a genetic disorder that causes the production of abnormal hemoglobin
  • thalassemia: a genetic disorder that affects your body’s ability to produce normal hemoglobin
  • congenital spherocytic anemia: a disorder of your red blood cell membranes that are shaped like a sphere

If the results of your test are abnormal, your healthcare provider will probably perform more tests to determine exact cause behind your hemolytic anemia. These additional tests may be simple blood or urine tests, or they may include testing your bone marrow.

Risks of the Serum Hemoglobin Test

The only risks involved in this test are those always related to a blood draw. For example, you will probably feel slight pain when the needle is inserted to take your blood sample. You might bleed a little when the needle is removed or develop a small bruise in the area.

Rarely, a blood draw may have more serious outcomes, such as excessive bleeding, fainting, or an infection at the injection site.


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