Description
Lactate dehydrogenase (LDH) is an oxidoreductase which catalyses the conversion of lactate to pyruvate. It consists of 4 subunits which may be of 2 different types; M (muscle) and H (heart) formerly known as A and B respectively. Five different isoenzymes are therefore possible, depending on the subunit composition: LDH-1 (H4), LDH-2 (H3M), LDH-3 (H2M2), LDH-4 (HM3) and LDH-5 (M4). LDH-1 and LDH-2 are predominant in the heart, while LDH-4 and LDH-5 predominate in skeletal muscles and the liver.
Indications
LDH activity is highly increased in megaloblastic and pernicious anaemia, carcinomatosis, viral hepatitis, shock, hypoxia and extreme hyperthermia. Moderately increased activity is seen in cirrhosis, obstructive jaundice, renal disease, skeletomuscular disease, neoplasm, and congestive heart failure. In addition, increased LDH is seen in any cellular injury, myocardial, pulmonary or renal infarction, leukaemia, haemolytic anaemia, sickle cells disease, lymphoma and acute pancreatitis. Decreased activity is associated with LDH genetic deficiency.
Sample Type, Quantity & Conditions
1 ml Serum 1 ml Li, Na, NH4+-Heparin Plasma Stability: 7 Days at 15-25 °C 4 Days at 2-8 °C 6 Weeks at -20 °C
Special Precautions
Avoid contamination with platelets when collecting plasma samples. Samples should be analyzed promptly. Certain diseases (e.g. hepatopathy, diseases of skeletal muscles, malignant tumors) may lead to incorrect LDH value in cooled and frozen samples.
Normal Range
Male: 135 - 225 U/L 2.25 - 3.75 μkat/L Female: 135 - 214 U/L 2.25 - 3.55 μkat/L Child (2-15 Years): 120 - 300 U/L 2.00 - 5.00 μkat/L Newborns (4-20 Days): 225 - 600 U/L 3.75 - 10.00 μkat/L
