<prompt> The predominant isozyme of LDH in Lung is:LD-1LD-2LD-3LD-5  <response>: Isoenzymes of Lactate Dehydrogenase: Lactate dehydrogenase is a tetrameric enzyme and consists of four subunits. These subunits can occurs in two isoforms i.e. H isoform for hea, M isoform for muscle. LDH-1 4H - in the hea and RBCs LDH-2 3H1M - in the reticuloendothelial system LDH-3 2H2M - in the lungs LDH-4 1H3M - in the kidneys, placenta, and pancreas LDH-5 4M - in the liver and striated muscle Normal value of LDH in serum is 100-200 UL. LDH level is 100 times more inside the RBC than in plasma, and therefore minor amount of hemolysis will result in a false positive test. Ref: Harpers Illustrated Biochemistry, 26th Edition, Page 57; Textbook of Biochemistry By Vasudevan, 5th Edition, Page 53 