Lactate Dehydrogenase (LDH)

The Lactate Dehydrogenase (LDH) Test measures the level of a specific protein—an enzyme—found in almost every cell in your body. LDH plays a vital role in converting sugar into energy for your cells to use. Under normal conditions, LDH stays tucked inside cells, however, when cells are damaged or destroyed, they spill LDH into the bloodstream or other body fluids.

In a clinical setting, LDH is a powerful prognostic indicator. While it always does not tell a doctor where the damage is located—since it is so widespread, it tells them how much damage is occurring. High levels serve as a red flag, prompting further investigation through LDH isoenzymes, which can pinpoint the specific organ involved (e.g., LDH 1 for the heart or LDH 5 for the liver). This makes the LDH test an essential first-line tool for monitoring disease severity and ensuring that treatment plans are effectively stopping cellular destruction.