The Ham test is a

blood test A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via fingerprick. Multiple tests for specific blood components, such as a glucose test or a cholester ...

used in the diagnosis of paroxysmal nocturnal hemoglobinuria (PNH). Patient

red blood cells Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek language, Greek ''erythros'' for "red" and ''k ...

(RBCs) are placed in mild acid; a positive result (increased RBC fragility) indicates PNH or

congenital dyserythropoietic anemia Congenital dyserythropoietic anemia (CDA) is a rare blood disorder, similar to the thalassemias. CDA is one of many types of anemia, characterized by ineffective erythropoiesis, and resulting from a decrease in the number of red blood cells (RBCs) ...

. This is now an obsolete test for diagnosing PNH due to its low sensitivity and specificity. As one fourth of PNH cases progress to aplastic anemia, Ham's test is occasionally positive in AA.

References

{{med-diagnostic-stub Medical tests