Healthline states that low LDH levels indicate a lower than normal level of lactate dehydrogenase, an enzyme that aids in the conversion of sugar to energy, in the bloodstream. Low levels can be caused by genetic mutations or a large intake of vitamin C.
Healthline maintains that low LDH levels are not usually harmful. One genetic mutation that causes low LDH levels can result in occasional fatigue or muscle pain. Another possible mutation has no symptoms. Low levels are usually determined by a blood test, but in some cases, a urine or cerebrospinal fluid sample is used instead. The LDH enzyme is found in many of the tissues of the body.
MedlinePlus states that LDH tests are most accurate if the patient abstains from substances that could affect the results. These include pain relievers, fluorides, narcotics, some heart medications and some vitamins. LDH tests are typically ordered to check for a high LDH level, which is a sign of tissue damage, disease, circulation problems or cancer. A second test for LDH isoenzymes is used as a follow-up to pinpoint exactly which types of LDH enzymes are irregular. Because different types of LDH enzymes are found in different organs, this test helps medical professionals diagnose the specific location of tissue damage causing high LDH levels.