Lactate dehydrogenase (LD or LDH) catalyzes the reduction of pyruvate by NADH to form lactate and NAD+. The catalytic concentration is determined from the rate of decrease of NADH measured at 340 nm.

PREPARATION OF  WORKING SOLUTION

Prepare working solution by mixing Reagent R1 and Reagent R2 in the ratio 4:1 as per requirement.

REAGENT STORAGE & STABILITY

• The reagent kit should be stored at 2- 8 degree C and is stable till the expiry date indicated on the label.
• Ri and A2 are stable till expiry at 2-8 degree C:
• The working solution (4 Rj + 1 R2) is stable for 30 days at 2-8 degree C.
• DO NOT FREEZE THE REAGENT. Contamination of the reagents should be strictly avoided.

 SPECIMEN COLLECTION  & PRESERVATION

Collect the specimen in a clean & dry container. Although serum is preferred, plasma with Heparin or EDTA can be used. Hemolyzed samples should not be used since LDH activity in erythrocytes is 160 fold higher than in serum. The serum should be separated from the clot promptly. Samples should be assayed soon after collection. LDH is stable in serum or plasma for four days at 2 - 8 degree C. Do not freeze or expose the serum to high temperature as this may inactivate thermolabile LDH isoenzymes.

 PROCEDURE

• Reaction type: UV - Kinetic
• Reaction direction : Decreasing
• Wavelength : 340 nm.
• Flowcell temperature : 37 degree C
• Zero setting with : Distilled water
• Delay time: 60 seconds
• No. of readings : 4
• Interval : 30 seconds
• Blank absorbance limit: 1.000 Abs.
• Sample volume: 0.02 ml (20 [11)
• Working solution volume (4 R., :1 R2): 1.0 m I
• Factor: 8109
• Linearity: 2000 IU/1

Mix and aspirate. After the initial delay of 60 seconds, record the absorbance of the test at an interval of 30 seconds for the next 90 seconds at 340nm.

 The following factors are used for conversion:

• From 25 degree C to 30 degree C: 1.34 
• From 25 degree C to 37 degree C: 2.00