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Test Code LD ISOENZ Lactate Dehydrogenase (LD) Isoenzymes, Serum

Reporting Name

Lactate Dehydrogenase Isoenzymes, S

Useful For

Investigating a variety of diseases involving the heart, liver, muscle, kidney, lung, and blood


Differentiating heart-synthesized lactate dehydrogenase (LD) from liver and other sources


Aids in the diagnosis of myocardial infarction when used in combination with total creatine kinase (CK) and CK-MB


Investigating unexplained causes of LD elevations


Detection of macro-LD

Necessary Information

Patient's age is required.

Specimen Required


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 2 mL divided into 2 tubes each containing 1 mL

Specimen Type


Specimen Minimum Volume

0.75 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Ambient (preferred) 7 days
  Refrigerated  48 hours

Day(s) and Time(s) Performed

LD: Monday through Sunday; Continuously

LD isoenzymes: Tuesday, Thursday, Saturday; 10 a.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

LDI: Electrophoresis Densitometry

LD: Photometric Rate

Method Description

Photometric Rate:

Lactate and NAD+, in the presence of lactate dehydrogenase (LD), are converted to pyruvate and NADH. The rate at which NADH is formed is determined by an increase in absorbance and is directly proportional to enzyme activity.(Package insert: Roche LDH reagent, Indianapolis, IN, November, 1999)


Isoenzyme Electrophoresis:

The 5 isoenzymes of LD are separated by electrophoresis on agarose film. The serum samples are electrophoresed and separated LD isoenzymes are visualized using a specific chromogenic substrate. Densitometry is used to obtain relative quantification of each fraction. The fractions are numbered according to their electrophoretic mobility, LD-I being the most mobile.(Clinical Guide to Laboratory Tests. Third edition. Edited by NW Tietz, Philadelphia, WB Saunders Company,1995)

Reference Values


1-30 days: 135-750 U/L

31 days-11 months: 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

≥18 years: 122-222 U/L



I (fast band): 17.5-28.3%

II: 30.4-36.4%

III: 19.2-24.8%

IV: 9.6-15.6%

V (slow band): 5.5-12.7%

Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


83625-LD isoenzymes

LOINC Code Information

Test ID Test Order Name Order LOINC Value
LD_I Lactate Dehydrogenase Isoenzymes, S In Process


Result ID Test Result Name Result LOINC Value
LD Lactate Dehydrogenase (LD), S 14804-9
305 LD Isoenzymes, S 49279-3
3344 Total LD Activity 14804-9
2282 I, Heart 2536-1
2283 II 2539-5
2285 III 2542-9
2286 IV 2545-2
2287 V, Liver 2548-6

Reject Due To


Mild reject; Gross reject


Mild OK; Gross OK





Profile Information

Test ID Reporting Name Available Separately Always Performed
LD Lactate Dehydrogenase (LD), S Yes Yes
LDI LD Isoenzymes, S No Yes


1. If not ordering electronically, complete, print, and send a Gastroenterology and Hepatology Test Request Form (T728) with the specimen (

2. Biochemical Genetics Patient Information (T602) in Special Instructions.