People living with chronic illnesses are often encouraged to learn as much as they can about their condition. If you’re researching paroxysmal nocturnal hemoglobinuria (PNH), you might come across mentions of the Ham test and wonder why it’s not commonly discussed today.

Once a common method for diagnosing PNH, the Ham test is now rarely used, but you may still hear it mentioned or read about it in older articles. Read on to learn more about the Ham test and why doctors now use other tests instead to diagnose PNH.

How Did the Ham Test Work?

The Ham test was developed by Thomas Ham, based on his belief that sleep caused the blood of people with PNH to become more acidic. To perform the test, doctors would take a blood sample from someone experiencing symptoms and expose the red blood cells (RBCs) to a mild acid solution. If the cells became fragile or broke apart, this indicated that the person might have PNH. Further tests were usually needed to confirm the diagnosis or rule out other blood disorders.

Formerly used to diagnose PNH, the Ham test involved exposing red blood cells from a blood sample to a mild acid.

If the red blood cells weren’t damaged by the acid, this result indicated that another condition was likely causing the symptoms.

How Is PNH Diagnosed Now?

As medical science advanced, the Ham test became obsolete, along with tests called the sucrose lysis test and the gel card technique. Researchers found that other tests do a better job of identifying the cause of symptoms and determining a diagnosis of PNH.

Flow Cytometry

The current gold standard (best method) for diagnosing PNH is flow cytometry. This test looks for specific proteins attached to red blood cells. These anchored proteins are either missing or reduced in people who have PNH.

To perform flow cytometry, a doctor takes a blood sample and sends it to a lab. A technician treats the blood sample with special chemicals that highlight certain proteins in or on the cells. The sample is then run through a special machine that provides information about the cells. A pathologist (a doctor specializing in the study of body fluids and tissues) will look at these results and tell your doctor what they mean.

Flow cytometry is now considered the gold standard for diagnosing PNH.

Besides determining if particular proteins are present in your RBCs, these medical professionals also look for a certain chemical in leukocytes — white blood cells that are part of your immune system.

Bone Marrow Tests

Your doctor may choose to biopsy your bone marrow, which involves taking a sample of the soft, spongy tissue for testing. Bone marrow tests aren’t generally necessary to confirm PNH, but they help rule out other disorders, and some doctors consider them to be part of a thorough diagnostic process. These tests help detect conditions related to PNH, like aplastic anemia or bone marrow failure (when bone marrow can’t make enough RBCs).

Complete Blood Count With Differential

If your doctor orders a “CBC w/diff,” they’re requesting a complete blood count with differential. This laboratory test examines the different types of cells in your blood, counts how many of each type are present, and provides other details. For people with PNH, a CBC often reveals anemia (lower levels of hemoglobin, a protein in RBCs). In 40 percent of cases, a CBC may show pancytopenia, a condition in which all three types of blood cells (red blood cells, white blood cells, and platelets) are decreased. Doctors also use this test to rule out other blood disorders.

Kidney and Liver Tests

Your doctor may also check your kidneys and liver for signs of hemolysis, which occurs when your body is breaking down a lot of red cells. These diagnostic tests can also help identify whether your symptoms are caused by problems with kidney or liver function instead of PNH.

Urine Tests

If you have blood in your urine or signs of iron deposits, you may be more likely to be diagnosed with PNH. Testing for this is usually simple — you just need to pee in a cup, and your doctor will either test the urine sample in the office or send it to a lab to be analyzed.

Other Tests

Depending on your symptoms, your doctor may order additional tests. They may measure the number of reticulocytes (immature RBCs) in your bone marrow to see whether your body is producing new red blood cells at a healthy rate. They may also test for high levels of lactate dehydrogenase, a substance released when red blood cells are destroyed. Lastly, they’ll check your levels of haptoglobin, a protein that helps remove waste products from damaged red blood cells. Low haptoglobin levels could indicate an unusually high rate of RBC destruction.

You can always ask your doctor about the tests they’re ordering, why they’re needed, and what the results will reveal.

These tests, along with those discussed above, can help your doctor or hematology team make an accurate diagnosis of PNH. The results can also help your medical team understand how — and how much — the condition is affecting your body.

Speak With Your Doctor

If you were diagnosed with PNH in the past based on a Ham test, you might want to ask your doctor whether flow cytometry could provide additional insights.

If you’re in the process of being diagnosed with PNH or experiencing symptoms of the condition, understanding the tests involved can help you ensure you’re getting a comprehensive diagnosis. You can always ask your doctor about the tests they’re ordering, why they’re needed, and what the results will reveal. Being informed about your health empowers you to make sure you’re getting the best possible care.

Talk to Others Who Understand

On myPNHteam, the social network for people with paroxysmal nocturnal hemoglobinuria and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with PNH.

Have you ever had a Ham test for PNH? What other diagnostic tests did your doctor order? Share your experience in the comments below, or start a conversation by posting on your Activities page.