The following Flipped pattern of LDH blood levels are seen in Myocardial infarction:

(D) LDH1>LDH2[?]Lactate Dehydrogenase (LDH)oRises within 24 to 48 hours of MIoPeaks at 3 - 5 days and returns to baseline by 7-10 daysoUsefulness in patients who are admitted to hospital 2-3 days after onset of symptomsoLevel of LDH-1 greater than LDH-2 = myocardial necrosisoNormally, the level of LDH-2 Is higher than the LDH-1. 29-39% of total activity against 14-26%oAn LDH-1 level higher than that of LDH-2, a phenomenon known as 'flipped LDH', is strongly indicative of a myocardial infarction.oThe flipped LDH usually appears within 12-24 hours after a heart attack.oA normal LDH-1/LDH-2 ratio is considered reliable evidence that a heart attach has not occurred.[?]In normal serum, LDH2 (H3 M) predominant isoenzyme & LDHs is rarely seen.oIn myocardial infarction, LDH1 (H4 ) levels are greater than LDH2 , called flipped pattern.oMegaloblastic anemia (50 times upper limit of LDH1 & LDH2 ).oMuscular dystrophy, LDH5 (M4 ) is increased.oToxic hepatitis with jaundice (10 times more LDH5 )oMyocardial infarction (LDH1>LDH2)oMegaloblastic anemia... Marked | in LD activity-Up to 50 times the upper reference limit - ineffective-Erythropoiesis - release of LD1 & LD-2 isozymes.oLactate dehydrogenase, tetrameric enzyme with 4 subunits,o4 Subunits with 2 isoforms - H isoform (Heart) & M isoform (Muscle)-Heart & RBCs - LDH-1 (4H);-Reticuloendothelial system - LDH-2 (3H1M)-Lungs - LDH-3 (2H2M)-Kidneys, placenta, & pancreas - LDH-4 (1H3M)-Liver & striated muscle - LDH-5 (4M)oUses:-LDH levels are more in RBC-Helpful in assessment of Hemolysis/Tissue breakdownoFlipping effect:-Usually LDH 2 in predominant in serum & LDH 1 is predominant in heart-Higher levels of LDH 1 than LDH 2 (Flipped pattern) is suggestive of myocardial infarction-Damaged cardiac tissues release LDH 1 into bloodstream.