Internal Medicine

0521779407-21 CUNY1086/Karliner 0 521 77940 7 June 7, 2007 18:59

1482 Unstable Hemoglobins

tests

Blood

■Peripheral blood smear: hypochromia, poikilocytosis, anisocytosis,

reticulocytosis, basophilic stippling

■Increased indirect bilirubin

■Increased LDH

■Decreased haptoglobin

Specific Tests:

■Supravital stain (methylene blue) may show Heinz bodies (may be

minimal or absent if spleen is present)

■Isopropanol stability test may show excessive precipitation of abnor-

mal hemoglobin at 37 degrees C in 17% isopropanol.

■Heat stability test may show hemoglobin precipitation at 50

degrees C.

■Some unstable hemoglobin variants may be detected by hemoglobin

electrophoresis/isoelectric focusing.

■The above tests may be negative if the hemoglobin is too unstable to

be released from the bone marrow into the periphery. Tests may be

performed on bone marrow samples.

differential diagnosis

■Other hemolytic anemias

➣Glucose-6 phosphate dehydrogenase deficiency (low enzyme

levels)

➣Immune hemolytic anemia (Coombs positive)

➣Hereditary spherocytosis (positive osmotic fragility test)

➣Red cell membrane defects (characteristic morphologies on

peripheral smear)

➣Red cell enzyme defects (measure enzyme level)

■Thalassemias (hemoglobin electrophoresis)

■If nucleated red cells and teardrops on blood smear, consider con-

genital dyserythropoietic anemias, sideroblastic anemia (bone mar-

row aspirate and biopsy, including iron stain)

management

■Red cell transfusions for symptomatic anemia (hemolysis may be

exacerbated by illness, oxidant drugs)

■Splenectomy for: persistent severe anemia

➣risk of splenic rupture

➣hypersplenism