Lactate dehydrogenase isoenzyme 3 and hemolysis in sickle cell anemia: a possible correlation?

Recombinant factor VIII products and inhibitor development in previously untreated boys with severe hemophilia A. Lactate dehydrogenase isoenzyme 3 and hemolysis in sickle cell anemia: a possible correlation? The concept that lactate dehydrogenase (LDH) is a useful clinical marker of hemolysis in sickle cell anemia (SCA) is still a subject of debate. 1,2 Some previous data suggested that the increase in serum LDH in these patients was mainly due to tissue damage rather than hemolysis. 1,2 However, other authors had shown a clear correlation between LDH and plasma hemoglobin (Hb). 3,4 The 5 LDH iso-enzymes are separable by electrophoretic mobility and have different tissue origins: LDH-1 and LDH-2 are found in erythrocytes and cardiac muscle; LDH-3 in lymphatic tissue, platelets, lung, and the pancreas; and LDH-4 and LDH-5 in the liver and skeletal muscle. 5 Recently, a strong correlation was demonstrated between LDH and erythrocyte-derived microvesicles, a product of hemolyz-ing erythrocytes. 4,6 Nevertheless, there is scarce information about these isoenzymes in SCA; therefore we evaluated LDH and its iso-enzymes in the hemolytic process of SCA. We tested 40 consecutive SCA patients, with a median age of 30 years (P25-P75: 22 to 37), 28 (70%) women, who were assigned to 2 groups: sickle cell (SS) (20 patients without hydroxyurea [HU]) Table 1. Characteristics of the groups of patients with SS, patients in use of HU, and CG SS (n) SS-HU (n) CG (n) Results are expressed as median (P25-P75). Kruskal–Wallis with Dunn's Multiple Comparison Test. and SS-HU (20 patients who were using HU at the maximum tolerated dose of 27.4 mg/kg, P25-P75: 23.2 to 28.8). Twenty-two healthy individuals composed the control group (CG) with a median age of 31 years (P25-P75: 27 to 39), 13 (59%) female. Patients with painful crisis or red blood cell transfusion in the preceding 3 months, and pregnant women were excluded. Study approval was obtained from the Federal University of São Paulo, the institutional review board for these studies. Informed consent was provided according to the Declaration of Helsinki. Complete blood cell count (Cell-Dyn 370, Abbott Diagnostics) and serum level of LDH were obtained by routine methods (Cobas, Roche); LDH isoenzymes by electro-phoresis on agarose gel and specific enzymatic revelations (Interlab G26); plasma-Hb determination by spectrophotometry; erythrocyte-derived microvesicles by flow cytometry (FACSCalibur, BD Bio-sciences) 7 ; and haptoglobin by immunoturbidimetry (Olympus AU 640 system). Kruskal–Wallis and Spearman correlation tests were performed using GraphPad Prism 5 (GraphPad …