Clinical Utilities
Spherocytes are osmotically fragile cells that rupture more easily in a hypotonic solution than do normal red blood cells. Because they have a low surface area: volume ratio, they lyse at a higher osmolarity than do normal discocyte (RBCs). Cells that have a larger surface area: volume ratio, such as target cells or hypochromic cells are more resistant to lysing. After incubation, an increase in hemolysis is seen in hereditary spherocytosis. The test is helpful in confirming or detecting mild spherocytosis. Infrequently, other hemolytic disorders may also be associated with positive tests, as in patients with congenital nonspherocytic hemolytic anemia due to glucose-6-phosphate dehydrogenase (G-6-PD) or pyruvate kinase deficiency. Patients with an immunohemolytic anemia, or who have recently received a blood transfusion may also have increased RBC lysis.

CPT Codes
85557

Reference Range
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Component Information