Clinics and Departments

Laboratory Services

Lab Dept:

Chemistry

Test Name:

LDH ISOENZYMES

General Information

Lab Order Codes:

LDHI

Synonyms:

Lactate Dehydrogenase Isoenzymes, Serum

CPT Codes:

83625 – LD; isoenzymes, separation and quantitation
83615 – Lactate dehydrogenase (LD)

Test Includes:

LD, total plus isoenzymes

Logistics

Test Indications:

May be useful in liver disease and conditions causing hemolysis. Differentiating heart from liver and other sources of LDH. Used by many clinicians in the diagnosis of myocardial infarctions in combination with total creatine kinase (CK) and CK-MB.

Lab Testing Sections:

Chemistry - Sendouts

Referred to:

Mayo Medical Laboratories (Test# 8679/LD_I)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

1 - 4 days

Special Instructions:

None

Specimen

Specimen Type:

Blood

Container:

Red top tube

Draw Volume:

3 mL (Minimum: 2.5 mL) blood

Processed Volume:

1 mL (Minimum: 0.75 mL) serum

Collection:

Routine venipuncture

Special Processing:

Lab Staff: Centrifuge specimen, remove serum aliquot into a screw-capped round bottom plastic vial. Store and ship at ambient temperatures. Specimen cannot be frozen. Forward promptly.

Patient Preparation:

None

Sample Rejection:

Hemolysis; thawed specimens; mislabeled or unlabeled specimens

Interpretive

Reference Range:

LD Total

Age

Males & Females (U/L)

1 – 30 days:

135 - 750

31 days – 11 months:

180 - 435

1 – 3 years:

160 - 370

4 – 6 years:

145 - 345

7 – 9 years:

143 - 290

10 – 12 years:

120 - 293

13 – 15 years:

110 - 283

16 – 17 years:

105 - 233

≥18 years:

122 - 222

LD Isoenzymes

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%

Critical Values:

N/A

Limitations:

A hemolyzed specimen is not acceptable as red blood cells contain much more LD than serum. Causes can include transportation via pneumatic tube, vigorous mixing or traumatic venipuncture. Tubes should be void of air bubbles to prevent minor hemolysis. LD activity is one of the most sensitive indicators of in vitro hemolysis. Hemolysis causes anomalous elevation of LD (1) such that any ex vivo hemolysis must be strictly avoided.

Freezing or prolonged storage at 4 degrees C (>12 hours) causes LD(5) to be lost.

Elevations of intermediate forms (LD2 and LD4) are rarely used to define a tissue of origin and such reports are largely anecdotal.

While increases in serum LD also are seen following an Myocardial Infarction, the test has been replaced by the determination of troponin.

Methodology:

Electrophoresis with densitometry, photometric rate

References:

Mayo Medical Laboratories Web Page January 2013

Updates:

8/23/2005: Method update, previously listed as Electrophoresis only.
5/9/2008: Specimen storage/transport previously listed as refrigerated.



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