Normally hemoglobin is maintained in a reduced state. Heinz bodies form when hemoglobin undergoes oxidation in vivo or in vitro.
Features of Heinz bodies:
(1) one or more round clumps of denatured hemoglobin within an erythrocyte measuring 1 to 3 microns in diameter
(2) usually attached to the red cell membrane
(3) not visible on a routine Wright-Giemsa stained smear
(4) visible with supravital staining (crystal violet or brilliant cresyl blue) as purple or blue inclusions
Causes of Heinz bodies in vivo:
(1) defect in red blood cell enzyme (G6PD deficiency, etc) that makes the erythrocyte susceptible to oxidation by certain chemicals or drugs (primaquine, quinacrine, sulfonamide, dimercaprol, methylene blue, trinitrotoluene, naphthalene, sulfones, nitrofurantoin, nitrodurazone, PAS, nalidixic acid, acetanilid)
(2) oxidative drug or chemical that overwhelms the normal enzymes that keep hemoglobin in a reduced state (chlorates, phenylhydrazine)
(3) unstable hemoglobin
(4) severe alcoholic liver disease with hemolytic anemia (Zieve syndrome)
During a hemolytic episode in G6PD deficiency the Heinz bodies are present initially but then disappear as affected red blood cells are cleared in the spleen or hemolyze.
(1) exclusion of other inclusions within red blood cells.
(2) exclusion of in vitro formation following storage of a specimen (testing should be done promptly after specimen collection)
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Specialty: Hematology Oncology, Clinical Laboratory