Lactic Dehydrogenase


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lactic dehydrogenase

[′lak·tik dē′hī·drə·jə‚nās]
(biochemistry)
An enzyme that catalyzes the dehydrogenation ofL-lactic acid to pyruvic acid. Abbreviated LDH.

Lactic Dehydrogenase

 

an enzyme of the oxidoreductase class; it catalyzes the reversible reduction of pyruvic acid to L-lactic acid with the participation of reduced nicotinamide adenine dinucleotide (NAD·H + H+) as a coenzyme:

Lactic dehydrogenase, extracted from the muscle tissue of vertebrates in crystalline form, is composed of four polypeptide sub-units (the molecular weight of one lactic dehydrogenase tetramer is 140,000). The equilibrium of the catalyzed lactic dehydrogenase reaction is strongly shifted toward the formation of lactic acid. The reaction requires the presence of NAD·H + H+ and proceeds in most animal tissues under anaerobic conditions. Cancer cells form one exception since a large amount of lactic acid is formed in these cells under aerobic conditions. Five isoenzymes of lactic dehydrogenase are known, which differ in amino acid composition as well as in certain physical, immunological, and catalytic properties. The determination of lactic dehydrogenase activity in blood plasma is of significant diagnostic value. Lactic dehydrogenase has been detected in Lactobacillaceae that catalyze the formation of D-lactic acid with the participation of reduced NAD.

IU. N. LEIKIN

References in periodicals archive ?
In many children additional tests included: serum creatine phosphokinase (CPK), lactic dehydrogenase (LDH), ammonia and bilirubin; presence/titres of IgM class antibodies against a number of viruses (known to be associated with acute brain disease) and Leptospira species; blood, CSF and urine bacterial culture; viral isolation studies on serum, CSF, urine and visceral specimens.
Lactic dehydrogenase: a biochemical marker for preeclampsia-eclampsia.
Serum tumor markers were detected before operation and the results were as following: CA 125 34.20 U/ml, (normal range: 0–35.00 U/ml), CA 199 34.11 U/ml (normal range: 0–39.00 U/ml), alpha-fetoprotein (AFP) >1210.0 ng/ml (normal range: 0–7.0 ng/ml), beta-human chorionic gonadotropin ([sz]-hCG) 12.81 U/L (normal range: 0–2.90 U/L), and lactic dehydrogenase (LDH) 204 U/L (normal range: 109–245 U/L).
Other test results (liver and renal function, serum folate and vitamin B12 levels, lactic dehydrogenase levels, C-reactive protein, serum protein electrophoresis, direct and indirect Coombs tests, and antinuclear antibody tests) were within normal limits, as were viral serologic test results (HIV, hepatitis B virus, hepatitis C virus, parvovirus B19).
WORK-UP: His erythrocyte sedimentation rate was over 130 mm/h (normal range, 1-15 mm/h), lactic dehydrogenase was 311 U/L (normal range, 118-273 U/L), and C-reactive protein was 21.8 mg/dL (normal range, 0-0.5 mg/dL).
The white blood cell count was 70,000 per [micro]L and the lactic dehydrogenase level was 12 000 U/L.
The alkaline phosphatase (4.4 [mu]kat, 262 U/L), lactic dehydrogenase (LDH) 7.55 [mu]kat, 453 U/L) and aspartate aminotransferase (AST) (88 U/L) were all elevated.
Blood sample was sent for serum amylase and lactic dehydrogenase.
Laboratory studies showed an elevation of lactic dehydrogenase (1,403 IU/L; normal 180-460 IU/L), ferritin (12,727.0 ng/mL; normal 4.0-64.2 ng/mL), and soluble interleukin-2 receptors (1,660 U/mL; normal 145-519 U/mL).
On the 11th day, he is transported to the pediatric ICU, where the following abnormalities are noted: metabolic acidosis with compensatory tachypnea; hyponatremia; increased creatine levels, total bilirubin levels, and lactic dehydrogenase levels; decreased albumin levels; high triglyceride levels; and neutropenia with an absolute neutrophil count of 0.
(5,8,9,10) Additionally, lactic dehydrogenase was consistently elevated with an average value of 5162.4 UI/L.