ACIDIFIED SERUM (HAM) TEST - blood

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Specimen: 10 mL blood in lithium heparin; collection by laboratory staff.

Method: Washed red cells incubated with fresh acidified serum. Lysis measured as haemoglobin in supernatant.

Application: Investigation of haemolytic anaemia , recurrent haemoglobinuria, hypoplastic anaemia, other obscure anaemia.

Interpretation: Lysis with acidified patient and normal serum indicates paroxysmal nocturnal haemoglobinuria (PNH) and is due to abnormal sensitivity of PNH red cells to complement. Lysis with acidified normal (but not patient) serum is seen in a rare congenital dyserythropoietic anaemia (HEMPAS).

Reference: Rosse WF. Blood 1991; 78: 547-550. Dacie JV and Lewis SM. Practical Haematology. 8th ed. Churchill Livingstone 1995.

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