LACTATE DEHYDROGENASE TEST (LDH TEST)

LDH Test

Lactate dehydrogenase (LD or LDH) is an enzyme involved in energy production that is found in almost all of the body's cells. with the highest levels found in the cells of the heart, liver, muscles, kidneys, lungs, and in blood cells. It is released during tissue damage, it is a marker of common injuries and disease such as heart failure. 5 isoenzymes are recognised, named as LDH-1 to LDH-5. LDH-2 is usually the predominant form in the serum, LDH-1 in heart and LDH-5 in skeletal muscles.

Why is LDH blood test prescribed?

An LDH-1 level higher than the LDH-2 level (a "flipped pattern") suggests myocardial infarction damage to heart tissues releases heart LDH, which is rich in LDH-1, into the bloodstream.

High levels may be seen in:

• Haemolytic anaemia, Vitamin B12 deficiency anaemia
• Hypoxia, shock
• Infarction Myocardial, lung, bowel etc, Rhabdomyolysis
• Some cancers such as lymphomas, testicular cancer
• Acute liver, kidney and pancreatic diseases

Low levels may be seen in:

• Intake of high doses of Vitamin C Measuring LDH in fluid aspirated from a pleural/pericardial effusion can help in the distinction between exudates or transudates. The usual criterion (included in Light's criteria) is that a ratio of fluid LDH versus upper limit of normal serum LDH of more than 0.6(two thirds) indicates an exudate, while a ratio of less indicates a transudate.

Reference range

Adults

81 to 234 units/litre

Prior strenuous exercise, elevated platelet count and haemolysed samples can show falsely high LDH values.

The levels of LDH vary with age and from lab to lab.