The lactate dehydrogenase (LDH) test looks for signs of damage to the body's tissues. LDH is expressed extensively in body tissues, such as blood cells and heart muscle. For example: Strenuous exercise can cause temporary elevations in LD. What is a lactate dehydrogenase (LDH) test? · What is it used for? · Why do I need an LDH test? · What happens during an LDH test? · Will I need to. Lactate dehydrogenase (LDH) among many biochemical parameters represents a very valuable enzyme in patients with cancer with possibility for easy routine. LDH is also a non-specific marker of tissue turnover, which is a normal metabolic process.