LDH (Lactate Dehydrogenase) Test

An LDH test is performed to identify tissue or cellular damage in the body specifically to organs such as the heart (eg, heart attack or myocardial infarction), kidney, liver, skeletal muscles, brain or blood cells. If raised blood levels of LDH are observed, the doctor may order more specific investigations to confirm the location and severity of the problem.

LDH test is also used to monitor various conditions, such as liver diseases, kidney diseases, anaemia and certain cancers including blood cancer. This test is not considered very useful to diagnose a heart attack or myocardial infarction, as various other tests, such as troponin and creatine phosphokinase (CPK), are available, which provide more specific information on this condition than the LDH test.

LDH is a simple blood test. No special preparations or precautions are required for it. However, this test may be performed with other blood tests that may require special precautions such as fasting. A laboratory technician or healthcare provider should explain the procedure and requirement of this test to patients to make them comfortable before the test.

Certain medications may increase the levels of LDH in blood. These include anaesthetics, aspirin, clofibrate (for cholesterol), fluorides, pain medications, itraconazole (for fungal infection), narcotics, levodopa (for Parkinson’s disease) and procainamide. Intake of these medications may need to be stopped before an LDH test. Hence, it is useful to discuss with the doctor about any ongoing medications before this test.

LDH test is similar to other blood tests. Fasting is usually not required unless specified by the doctor. A healthcare professional or laboratory technician takes a blood sample from a vein most commonly from the arm or hand by inserting a sharp needle into it. About, 5-7 mL of blood is usually collected for performing this test. Mild pain or stinging sensations may be felt at the time of needle prick. Bleeding can be prevented by applying pressure at the site of needle prick using a cotton swab. It is important to inform the doctor if you notice any unusual signs or discomfort. The withdrawn blood sample is properly labelled and sent to a laboratory for analysis.

LDH in the blood is usually measured in international units per litre (IU/L).

Normal results: Normal levels of total LDH in the blood are 110-210 IU/L. Normal values of specific LDH fractions are provided below:

• LDH1: 17-27%
• LDH2: 28-38%
• LDH3: 17-28%
• LDH4: 5-15%
• LDH5: 5-15%

Normal levels of blood LDH may indicate that the body organs, in which LDH is usually present, are functioning properly and there is no evidence of tissue damage.

Abnormal results: LDH levels usually rise when there is tissue or cell damage in certain organs.

It may be a sign of some of the  following conditions:

• Myocardial infarction (heart attack)
• Pulmonary (lung) infarction
• Heart failure
• Liver diseases
• Hypothyroidism (low thyroid hormones)
• Lung diseases
• Damage to muscles
• Anaemia
• Kidney infarcts
• Acute pancreatitis
• Brain disorders
• Fractures or trauma
• Intestinal obstruction
• Shock
• Various cancers
• Eclampsia (convulsions during pregnancy)
• Taking various medications

Decreased levels of LDH are generally not considered harmful. The doctor may recommend additional tests or investigations to diagnose the underlying condition.

Since high LDH indicates the presence of certain types of cancer, reduction in LDH levels in such patients could be a sign of efficiency of treatment.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational perspective and is in no way a substitute for medical advice from a qualified doctor.