What is HAM Test / PNH Test?
The Ham test is a blood test that can help your doctor determine the condition of the red blood cells in your body. Dr. Thomas Ham designed it. The test can help your doctor diagnose certain types of acquired and congenital blood disorders. It involves soaking a blood sample in a mild acid to test the fragility of your blood cells.
Doctors don’t use the Ham test very often. The flow cytometry test is gradually replacing it.
What is the purpose of the Ham test?
One drop of your blood contains millions of red blood cells. They constantly move through your circulatory system, delivering oxygen to your organs and tissues and removing waste. Healthy red blood cells are vital for your body’s organs to work properly. Their red color comes from a chemical called hemoglobin. This is a protein that carries iron and transports oxygen. Your red blood cells die around every 120 days, and your bone marrow is constantly producing new ones.
Your doctor may use this test to help diagnose paroxysmal nocturnal hemoglobinuria (PNH) or congenital dyserythropoietic anemia (CDA). These are both blood conditions.
How do you prepare for the Ham test?
No special preparations are necessary for this test. You should tell your doctor if you’re taking any blood thinners, such as warfarin (Coumadin). Your doctor may advise you to stop taking certain medications.
What happens during the Ham test?
You’ll need to provide a sample of blood from your arm. This involves the following steps:
- A healthcare provider will clean the site.
- They’ll insert the needle into your vein and draw your blood into an attached tube.
- When they’ve drawn enough blood for a sample, they’ll remove the needle and bandage the site.
- They’ll then send the blood sample to a laboratory for analysis.
What is PNH Test?
PNH is a rare, acquired stem cell disorder that results in episodic intravascular hemolysis, hemoglobinuria, hemolysis, and venous thrombosis. A somatic mutation causes loss of cell surface linkage proteins, which results in loss of complement regulatory proteins on the red blood cell surface. PNH may occur de novo, but it is also associated with aplastic anemia and may evolve into aplastic anemia after an indeterminate amount of time.
PNH is a rare clinical presentation, estimated to occur in the range of 1-10 cases per million. It is primarily a disease of adults and may have an insidious onset. All patients, however, are anemic (usually seriously so). They may describe dark urine after sleeping. However, this is actually a less likely presentation than anemia. Hemolysis may occur chronically and throughout the day. Chronic renal failure and iron deficiency anemia may occur. Chronic urinary iron loss, expressed as hemosiderinuria, is a constant feature. Venous thrombosis is present in approximately one-third of patients and is related to abnormal platelet function due to the loss of surface linkage proteins on platelets. Thrombosis is one of the more likely serious clinical scenarios for PNH patients, causing gastrointestinal pain, Budd-Chiari syndrome, headaches, and pulmonary thromboembolism.