Diagnostic Use
Can be useful in investigation of a variety of diseases involving the heart, liver, muscle, kidney, lung, and blood.
Sources of LDH:
- skeletal or cardiac muscle
- liver
- RBC
- Some tumours
- Haemolysed specimens
LDH is a relatively non-specific enzyme which has been largely superseded by alternative biochemical markers.
This test is of limited value in the diagnosis of myocardial infarction. It must be remembered that the enzyme activity will not start to rise until 12 – 24 hours after infarction. Testing too early will give a false negative result. If in doubt, take another sample for analysis about 4 – 6 hours later. The peak elevation of LD enzyme activity will occur 48 – 72 hours after infarction and levels will usually remain elevated for 7 – 12 days.
LDH is also increased by skeletal muscle damage. Occasionally useful in assessing patients with liver disease. Increased in haemolysed specimens, in anaemias due to haemolysis or ineffective erythropoiesis, and in some malignancies.
Test Method
Principle: UV Assay
Analysers: Roche Diagnostics Cobas c503
Reagents: LDHI2
Limitations / Interference
Falsely high values can be caused by haemolysis or delayed separation of the sample.