Characterisation of abnormal lactate dehydrogenase isoenzyme with the semi-automated hydrasys electrophoresis system

Abstract

Macroenzymes are complexes of serum enzymes with a plasma protein, having higher molecular weight with prolonged half-life. Their presence can cause an elevation in the serum enzyme levels, possibly leading to misdiagnosis. Herein we present a 30-year-old man found with persistent elevation of (lactate dehydrogenase) LDH level measuring 885–1083 IU/L in a routine health check-up. Other laboratory findings including complete blood counts, routine chemistries, liver function tests and serological tests for hepatitis virus were not remarkable. Radiological studies including abdominal ultrasonography also showed no significant finding. The electrophoresis of LDH isoenzymes was performed with the Hydragel Iso-LDH kit used in conjunction with the semi-automated Hydrasys gel electrophoresis system, and the electrophoretic separation showed abnormal migration patterns of LDH2 and 3 isoenzymes with densely stained LDH3. Immunoelectrophoresis of LDH isoenzyme with anti-human IgG, IgA, IgM, kappa and lambda light chain antibodies was performed to identify the antibodies bound to LDH. The patient’s LDH was presented to be bound to IgA and kappa light chain. This modified immunoelectrophoresis with semi-automated system could be useful to characterise these kinds of abnormal LDH isoenzyme patterns. Macroenzymes are complexes of serum enzymes with a plasma protein, having higher molecular weight with prolonged half-life. Their presence can cause an elevation in the serum enzyme levels, possibly leading to misdiagnosis. Herein we present a 30-year-old man found with persistent elevation of (lactate dehydrogenase) LDH level measuring 885–1083 IU/L in a routine health check-up. Other laboratory findings including complete blood counts, routine chemistries, liver function tests and serological tests for hepatitis virus were not remarkable. Radiological studies including abdominal ultrasonography also showed no significant finding. The electrophoresis of LDH isoenzymes was performed with the Hydragel Iso-LDH kit used in conjunction with the semi-automated Hydrasys gel electrophoresis system, and the electrophoretic separation showed abnormal migration patterns of LDH2 and 3 isoenzymes with densely stained LDH3. Immunoelectrophoresis of LDH isoenzyme with anti-human IgG, IgA, IgM, kappa and lambda light chain antibodies was performed to identify the antibodies bound to LDH. The patient’s LDH was presented to be bound to IgA and kappa light chain. This modified immunoelectrophoresis with semi-automated system could be useful to characterise these kinds of abnormal LDH isoenzyme patterns.