Ham Test

The Ham test, or acidified serum lysis test, is performed to determine the cause of undiagnosed hemolytic anemia, hemoglobinuria, and bone marrow aplasia. This test determines the stability of the red blood cell (RBC) membrane. It helps establish a diagnosis of paroxysmal nocturnal hemoglobinuria (PNH), a rare hematologic disease.

Purpose

• To help establish a diagnosis of PNH.
• To determine the cause of undiagnosed hemolytic anemia and bone marrow aplasia.

Patient Preparation

• Explain to the patient that this test helps determine the cause of his anemia or other signs.
• Advise him that he needn't restrict food or fluids.
• Tell him that the test requires a blood sample and who will perform the venipuncture and when.
• Reassure him that although he may experience transient discomfort from the needle puncture and the tourniquet, collecting the sample takes less than 3 minutes.

Procedure And Posttest Care

• Because the blood sample must be defibrinated immediately, laboratory personnel perform the venipuncture and collect the sample.
• If a hematoma develops at the venipuncture site, apply warm soaks.

Normal Findings

Normally, RBCs don't undergo hemolysis. Test results should be negatives.

Abnormal Findings

Hemolysis of RBCs indicates PNH.

Interfering Factors

• Blood containing large numbers of spherocytes (possible false-positive)
• Blood from patients with congenital dyserythropoietic anemia (false-positive)