NEET PG Medical – 2017 – Question – 53
Which option best explains “Flipping effect”?
A> LDH 1 > LDH 2
B> LDH2 > LDH1
C> LDH 2 > LDH 3
D> LDH 3 > LDH 2
Answer: Option A – LDH 1 > LDH 2
Explanation:
● Lactate dehydrogenase, tetrameric enzyme with 4 subunits,
● 4 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)
● Uses:
○ LDH levels are more in RBC
○ Helpful in assessment of Hemolysis / Tissue breakdown
● Flipping 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.
