What is the LDH test?

LDH is a blood test identifying levels of Lactic Acid Dehydrogenase (LDH) in the blood. LDH is an enzyme located in almost all body cells, but only a small LDH quantity can be detected in the blood. LDH releases into blood circulation and its levels increase when cells get impaired or damaged. LDH is used as a general marker to indicate cell impairment. It is usually the overall LDH that is measured in the laboratory, but there is also the potential to identifyvarious LDH isoenzymes. Isoenzymes are LDH molecules which have very small differences among them and are produced by various tissues in the body. Depending on which isoenzyme is high, it is possible to identify which organ has cell damage. There are 5 different LDH isoenzymes used in the everyday clinical practice.

When is the LDH test performed?

When the physician suspects there is cell or tissue damage, an LDH test will be ordered to identify the severity of the condition. Also, the determination of isoenzymes can help in setting the diagnosis, by identifying the organs involved. After the diagnosis, in some diseases, the measurement of LDH at regular time intervals can be used for monitoring the progression of the disease.  It is also a very good marker for evaluating response to therapy.

LDH increases in many diseases and is used by other medical specialties. In Urology, LDH is used as a marker for tissue damage in patients with renal, bladder and testicular cancer.

What preparation is needed for the LDH test?

No special preparation is needed. All that is needed to measure blood LDH is a simple small blood-sampling.

How is the LDH test performed?

Once obtained, the blood specimen is taken to the biochemical laboratory. LDH is estimated with the use of special analyzers.

How are the results of the LDH test interpreted?

Normal LDH values in adults are 200-480 IU/L. You should be aware that the following factors may affect the test results by increasing LDH blood values.

  • Intense physical exercise during the days before the LDH test.
  • Troublesome blood-taking and inappropriate preservation of the specimen until taken to the lab.