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Unit Code 8344:
Lactate Dehydrogenase (LD), Serum

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Useful For

Investigation of a variety of diseases involving the heart, liver,

muscle, kidney, lung, and blood

 

Monitoring changes in tumor burden after chemotherapy, although,

LD elevations in patients with cancer are too erratic to be of use in

the diagnosis of cancer

Clinical Information

LD activity is present in all cells of the body with highest concentrations in heart, liver, muscle, kidney, lung, and

erythrocytes. Serum LD is elevated in a number of clinical conditions.

Reference Values

1-30 days:  135-750 U/L

31 days-365 days:  180-435 U/L

1-3 years:  160-370 U/L

4-6 years:  145-345 U/L

7-9 years:  143-290 U/L

10-12 years:  120-293 U/L

13-15 years:  110-283 U/L

16-17 years:  105-233 U/L

> or = 18 years:  122-222 U/L

Interpretation

Marked elevations in LD activity can be observed in megaloblastic

anemia, untreated pernicious anemia, Hodgkin's disease,

abdominal and lung cancers, severe shock, and hypoxia.

 

Moderate to slight increases in LD levels are seen in myocardial

infarction (MI), pulmonary infarction, pulmonary embolism, leukemia,

hemolytic anemia, infectious mononucleosis, progressive muscular

dystrophy (especially in the early and middle stages of the disease),

liver disease, and renal disease.

 

In liver disease, elevations of LD are not as great as the increases

in aspartate amino transferase (AST) and alanine aminotransferase

(ALT).

 

Increased levels of the enzyme are found in about 1/3 of patients with

renal disease, especially those with tubular necrosis or pyelonephritis.

However, these elevations do not correlate well with proteinuria or other

parameters of renal disease.

 

On occasion a raised LD level may be the only evidence to suggest

the presence of a hidden pulmonary embolus.

Cautions

Red blood cells contain much more LD than serum. A hemolyzed

specimen is not acceptable. LD activity is 1 of the most sensitive

indicators of in vitro hemolysis. Causes can include transportation

via pneumatic tube, vigorous mixing, or traumatic venipuncture.

 

While increases in serum LD also are seen following an MI, the test

has been replaced by the determination of troponin.

Special Instructions and Forms

• An Expanded Algorithm for the Laboratory Evaluation of Suspected Multiple Myeloma 

Clinical Reference

Tietz Textbook of Clinical Chemistry. 4th edition. Edited by

C Burtis, E Ashwood, D Burns. Philadelphia, WB Saunders

Company, 2006; 21:601-603

Key