Lactate dehydrogenase (LDH) is an enzyme found in nearly all living cells. It plays a crucial role in the conversion of lactate to pyruvate in cellular respiration. Its presence is widespread across different tissues, including the heart, liver, kidneys, muscles, and blood cells. Due to its ubiquitous nature, LDH is often used as a marker for tissue damage and is an important biomarker in the field of toxicology.