LDH (lactic dehydrogenase): What is it for, values ​​(and high or low LDH)

LDH (lactic dehydrogenase) is an enzyme present within the cells responsible for glucose metabolism in the body, being found in almost all body tissues, but more in the muscles, liver, kidneys and red blood cells.

LDH, also known as lactate dehydrogenase, may have its levels increased when there is any changes in the heart or liver, or infections, or have lower levels due to dehydrogenase lactate deficiency, for example.

Also read: 13 exams to evaluate the liver (and how is the preparation)

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Although LDH is useful for identifying changes, it is important that the result is evaluated by the doctor along with other laboratory results to confirm the diagnosis and thus guide the best treatment.

So that Serve

The LDH exam serves to assist in the diagnosis and/or monitor the treatment of:

• Tissue damage;
• Changes in the liver, lungs or kidneys;
• Heart problems or myocardial infarction;
• Pulmonary embolism;
• Brain or spinal cord inflammation such as encephalitis or meningitis;
• Muscular dystrophy;
• Severe infections, mononucleosis or HIV.

In addition, LDH examination helps monitor chemotherapy or radiotherapy treatment and evaluate the severity of some cancers.

Also read: Tumor markers: what they are, what they serve and types (with table)

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How to prepare for the exam

To do the LDH exam, most of the time, it is not necessary to fast or any other type of preparation, however, some laboratories indicate that the person must be at least 4 hours of fasting.

Therefore, before you perform the exam is important to inform yourself in the laboratory which is the procedure, in addition to informing the use of medicines.

How the LDH Exam is done

The LDH exam is done by collecting a blood sample collected in the laboratory or in hospitals.

Depending on the objective of the exam, a sample of the cephalorean liquid can also be collected through lumbar puncture. Understand how lumbar puncture is made.

In addition, LDH levels in the abdominal cavity liquid may be evaluated, collected by pacentesis, or liquid of the pleural space in the lungs, through thoracocntesis.

Also read: Thoracocntesis: what it is, what it is for and how it is done

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Reference values

The normal LDH reference values ​​in the blood are:

Normal values ​​of dehydrogenase lactate may vary according to the laboratory in which the exam was done.

How to understand the result

The results of the LDH exam should be evaluated by the doctor who requested the exam, taking into account physical examination, symptoms presented by the person, general health and other laboratory tests.

What can be high LDH

The main causes of high LDH are:

• Hemolytic or megaloblastic anemia;
• Hepatitis or cirrhosis in the liver;
• Obstructive jaundice;
• Myocardial or pulmonary infarction;
• Muscle injury or muscle dystrophy;
• Pancreatitis;
• Septic shock;
• Meningitis, encephalitis, mononucleosis, covid-19 or HIV.

In addition, LDH may be high in some cancers, such as melanoma, testicle cancer, multiple myeloma, lymphomas or leukemia, for example.

Increased LDH is usually indicative of injury to organs or tissues being released in the bloodstream in these cases.

However, LDH may also be increased due to intense physical activity, use of some medications and pregnancy.

What can be low LDH

Low LDH in the blood is usually not worrying and is not related to diseases, not being a reason for investigation.

In some cases, LDH decreased may be related to excess vitamin C or E, and the person’s eating habits may be recommended.

In addition, LDH may be low in cases of dehydrogenase lactate deficiency.

LDH Types

LDH can be divided into 5 types, known as isoenzymes, according to its location in the body, such as:

• LDH-1which is present in the heart, red blood cells and kidneys;
• LDH-2which can be found in the heart, to a smaller quantity, and in leukocytes;
• LDH-3which is present in the lungs;
• LDH-4which is found in the placenta and pancreas;
• LDH-5which is found in the liver and skeletal muscle.

Identification of LDH isoenzyme through laboratory tests helps the doctor know the organ that is affected and better guide treatment.

Clinical Review:
Marcela Lemos
Biomedical

Master in Applied Microbiology, with qualification in clinical analysis and graduated from UFPE in 2017 with professional registration at CRBM/ PE 08598.