lactate dehydrogenase

• LD is mostly a liver enzyme, will be increased in liver disorders
• LD migration from fastest to slowest: HHHH, HHHM, HHMM, HMMM, MMMM, LD6
• LD1 - HHHH
• LD2 - HHHM
• LD3 - HHMM
• LD4 - HMMM
• LD5 - MMMM
• LD6 - alcohol dehydrogenase
• • LD1: HHHH
  • Makes up 14-26% of total LD
  • Found in cardiac tissues and red cells
• • LD2: HHHM
  • Makes up 29-39% of total LD
  • Found in renal cortex
• • Usually there is more LD2 than LD1, but when pt has MI, more LD1 is released, LD1 will be greater than LD2, this is called the “LD flip”
• • LD3: HHMM
  • Makes up 20-26% of total LD
  • Found in pulmonary involvement of diseases, carcinomas 
• • LD4: HMMM
  • Makes up 8-16% of total LD
  • Liver and skeletal muscle
• • LD5: MMMM
  • Makes up 6-16% of total LD
  • Liver and skeletal muscle
• method of choice for LD assay is forward method
• backward assay proceeds 3x faster than the forward assay
• • Hemolysis interferes with LD assay as the concentration of LD in red cells is 100-150x greater than in the serum
• cold temperature may interfere with LD assay; can only test samples stored at RT