Lactate deoxygenase has five isoenzyme forms, namely LDH1, LDH2, LDH3, LDH4, and LDH5, which can be separated by electrophoresis. The human heart, kidney and red blood cells are most LDH1 and LDH2. Liver and striated muscles are dominated by LDH4 and LDH5. There are more LDH3 in the spleen, pancreas, thyroid and adrenal glands. Lactate dehydrogenase isoenzyme is one of the indicators for observing myocardial disease, hepatobiliary disease and the like.

Basic Information

Specialist classification: cardiovascular examination classification: biochemical examination

Applicable gender: whether men and women apply fasting: fasting

Tips: Before the examination, the diet is light and alcohol is prohibited. Check for an empty stomach in the morning. Normal value

Agarose electrophoresis LDH2>LDH1>LDH3>LDH4>LDH5.

Clinical significance

(1) The results of lactate dehydrogenase isoenzymes must be combined with clinical symptoms to make an accurate judgment.

(2) LDH1 and LDH2 are elevated, and LDH1/LDH2>1 is found in acute myocardial infarction, hemolytic anemia, acute sickle cell anemia, megaloblastic anemia and other pernicious anemia. Acute renal cortical necrosis and various intravascular and extravascular hemolysis (if LDH1 is not elevated, hemolytic anemia can be ruled out).

(3) LDH5 increases skeletal muscle inflammation, injury and degeneration, liver damage (cirrhosis, hepatitis, liver hyperemia), cancer.

(4) Simple LDH1 raises bacterial cell tumors (eg, teratoma, testicular cell tumor, and ovarian necrotic cell tumor).

(5) The total LDH is elevated and the isoenzyme spectrum is normal in heart disease, liver disease, skeletal muscle disease, tumor and other functional disorders. The higher the LDH value in some cancer patients, the worse the prognosis.

(6) LDH2, LDH3 and LDH4 all increase a large number of platelet destruction (such as pulmonary embolism, massive blood transfusion, etc.), lymphatic diseases (such as infectious mononucleosis, lymphoma and lymphocytic leukemia).

High results may be diseases: hemolytic anemia, pulmonary embolism precautions

(1) Hemolysis can make LDH1/LDH2 meaningless.

(2) There are organizational differences in the distribution of LDH isoenzymes.

1LDH1: Myocardium (more than 50% of total enzymes)> Kidney> Pancreas> Diaphragm> Red blood cells.

2LDH5: liver (accounting for more than 50% of total enzymes)> skin> bone marrow> joint synovial fluid> white blood cells> platelets> bile.

3LDH3: lung>spleen>brain>intestinal>lymph>endocrine gland.

4LDHX (or LD-C2) is synthesized from mature testis and is unique to sperm. It is believed that LDHX is probably an alcohol dehydrogenase.

The H subunit mutation frequency of 5LDH is higher than that of the M subunit, and blacks are higher and more familial than whites. H1 and M1 are different in nature from H and M, so complex bands may appear on the electrophoresis spectrum.

Inspection process

Blood is taken immediately after venous blood collection. The principle of determination of lactate dehydrogenase isoenzyme is the same as that of agarose electrophoresis.

Required reagent: serum (serum should be separated from blood clot as soon as possible), store at room temperature for up to 3 days; LDH5 is the most unstable (more than 50 °C inactivation, 13% inactivation at 48h at normal temperature, 18% inactivation at 40 °C for 48h; -25 All the LDH4 and LDH5 were inactivated at °C overnight; the specimen was strictly forbidden to hemolyze; the substrate coloring solution was ready for use and should be placed away from light.

Method of operation: agarose electrophoresis.

Not suitable for the crowd

Generally no taboos.

Adverse reactions and risks

1. Infection: Pay attention to aseptic operation when collecting blood, avoid contamination of water and other parts at the blood collection site to avoid local infection.

2, bleeding: after the blood is given a full compression time, especially coagulopathy, bleeding tendency, to avoid local subcutaneous oozing, bruising and swelling.