Ham Test Overview
The ham test is a blood test designed by Dr. Thomas Ham that is used to determine the condition of the red blood cells in the body and to diagnose certain types of acquired and congenital blood disorders. The test uses a mild acid to soak a sample of blood to see how fragile the blood cells become in this type of environment.
The ham test is not administered very often as it is gradually being replaced by the flow cytometry test.
Purpose of the Ham Test
Just one drop of your blood contains millions of red cells. They are constantly moving through your circulatory system, transporting oxygen to all your organs and tissues and removing waste. Healthy red blood cells are vital for proper functioning of all your body’s organs. Their red color comes from a chemical called hemoglobin. This is a protein that carries iron in the blood, which is responsible for transporting the oxygen. Your red blood cells die around every 120 days, and your bone marrow is constantly producing new ones.
Your doctor may administer this test to help diagnose paroxysmal nocturnal hemoglobinuria or congenital dyserythropoietic anemia, both of which are blood conditions.
Where and How the Test Is Administered
Your doctor will need to take a sample of blood from your arm. First, the site will be cleaned with a swab coated with rubbing alcohol. The needle will then be inserted into a vein and a tube will be attached to fill with blood. When enough blood has been drawn for a sample, the needle is removed and the site is covered with a pad. The blood sample will then be sent to a laboratory for analysis.
Understanding the Results
If the red blood cells do not become fragile in the acid solution, your result is normal. A normal result will show as a negative reading.
Abnormal results may be caused by one of the following two conditions:
Paroxysmal Nocturnal Hemoglobinuria
This is a rare acquired disease (not genetic) that causes the red blood cells to die prematurely and new cells to be produced incorrectly. The red cells become sensitive to damage by another substance in the blood. This disorder affects red blood cells, white blood cells, and platelets. White blood cells fight infection. Platelets are tiny blood cells that prevent bleeding. This acquired disease affects both men and women, and most commonly occurs in early adolescence. The treatment for this disorder is iron replacement. Steroids may also been used. In extreme cases bone marrow transplantation has been used to treat the disorder. Symptoms of this disorder include the following and other symptoms common to anemia:
- recurring infections
- dark-colored urine, particularly in the morning
- shortness of breath
- abnormally pale skin
- back pain
- an increase tendency for venous blood clots(thrombosis)
Paroxysmal nocturnal hemoglobinuria is often treated with warfarin (Coumadin) to thin the blood and reduce the risk of thrombosis.
Congenital Dyserythropoietic Anemia (CDA)
This blood disease is inherited. It is rare. It is categorized within the types of anemia where there is reduced hemoglobin synthesis called thalassemia, It causes a shortage of red blood cells in the body due to decreased production, preventing the circulatory system from transporting adequate amounts of oxygen to the organs and tissues. Symptoms of this disorder include all the symptoms common to anemia including:
- dizzy spells
- abnormally pale skin
- yellowing of the skin(jaundice)
- liver disease
What Are the Risks of the Test?
As with any blood test, there are minimal risks of experiencing minor bruising at the needle site. In rare cases, the vein may become swollen after blood is drawn. If this occurs, it can be treated by applying a warm compress to the spot several times each day. Ongoing bleeding can be a problem if you suffer from a bleeding disorder, or if you are taking blood-thinning medication such as warfarin (Coumadin) or aspirin.
Preparation for the Test
There are no special preparations necessary for this test. You should tell your doctor if you are taking any blood-thinning drugs such as warfarin (Coumadin). Your doctor may advise you to stop taking certain medications.
What to Expect After the Test
If you have been diagnosed with CDA, your doctor will need to determine which of the three types you have:
- CDA type I: This variant causes mild anemia and is usually diagnosed in early childhood. It can cause iron overload and is usually treated with chelation therapy, which helps remove excess iron from the body. Yellowing of the eyes and skin (jaundice) is usually seen.
- CDA type II: This variant may be mild to severe and is usually diagnosed in the early teens. It can lead to gallstones, heart disease, diabetes and cirrhosis.
- CDA type III: This causes relatively mild symptoms and is usually diagnosed during adulthood. It may lead to vision impairment and cancer of the white blood cells.
Congenital dyserythropietic anemia is often treated with blood transfusions. Patients must also take medicines to remove the excess iron that builds up in the body. In extreme cases bone marrow transplant can be performed. Gene therapy has not yet proven to be effective.