What it measures
Lactate dehydrogenase (LDH) is an enzyme found in almost every tissue, including red blood cells, muscle, liver and heart. When cells are damaged it leaks into the blood, so the level is a general sign of tissue damage rather than pointing to one organ.
Why people test it
- Used as a general marker of tissue damage, read alongside other results to find the source.
- Measured when looking into the breakdown of red blood cells (haemolysis).
- Monitored in some blood disorders and cancers.
- Rises after hard or unaccustomed exercise, as stressed muscle releases it.
Typical range
Ranges vary by lab, method, age and sex, and your report shows the lab's own range. One NHS trust gives an adult upper limit of 248 U/L for men and 247 U/L for women. Source: Worcestershire Acute Hospitals NHS Trust: LDH.
Finger-prick or vein?
A vein draw is usually advised, and providers offer it that way. Red blood cells hold a lot of LDH, so a haemolysed sample, more common with finger-pricks, reads falsely high.