Lactate Dehydrogenase

AsseyMethod: Photo Colorimetric
Abbrevation: LDH
Sector: Biochemistry
SampleType: S
S.Vol: -
Transport: at RT
Storage: at 25˚c do not refrigerate or freez the sera
Test Name: Lactate Dehydrogenase
Normal Range: -

This test is related to
Why get tested?

To help identify the cause and location of tissue damage in the body, and to monitor its progress. LDH is elevated in a wide variety of conditions reflecting its wide spread tissue distribution. Historically, has been used to help diagnose and monitor a heart attack, but troponin has replaced LDH in this role.

When to get tested?

Along with other tests, when your doctor suspects that you have an acute or chronic condition that is causing tissue or cellular destruction and wants to identify and monitor the problem.

Sample required?

A blood sample taken from a vein in your arm

Test preparation needed?


What is being tested?

Lactate dehydrogenase (LDH, or LD) is an enzyme found in almost all body tissues. Usually the concentration in the blood is low, because  it usually stays contained within the tissues’ cells. When cells are damaged or destroyed, however, they release LDH into the bloodstream, causing blood levels to rise. For this reason, LDH is used as a general marker of injury to cells; it is not useful for determining which specific cells are damaged.

Elevations of LDH may be measured either as a total LDH or as LDH isoenzymes. Isoenzymes are slightly different molecular versions of the same enzyme. A total LDH level is an overall measurement of five different LDH isoenzymes. A high total LDH level reflects tissue damage but it is not specific to any one type of tissue, and so, by itself, it cannot be used to identify the underlying cause or its location.

Although there is some overlap, each of the five LDH isoenzymes tends to be concentrated in specific body tissues. Because of this, measurements of the individual LDH isoenzyme levels can be used, along with other tests, to help determine the disease or condition causing cellular damage and to help identify the organs and tissues involved. In general, the isoenzyme locations tend to be:

  • LDH-1 - heart, red cells, kidney, germ cells
  • LDH-2 - heart, red blood cells, kidney (lesser amounts than LDH-1)
  • LDH-3 - lungs and other tissues
  • LDH-4 - white blood cells, lymph nodes; muscle, liver (smaller amounts than LDH-5)
  • LDH-5 - liver, muscle

While all of the isoenzymes are represented in the total LDH, LDH-2 usually makes up the greatest percentage.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.