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Test Code LD ISOENZ Lactate Dehydrogenase (LDH) 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 (LDH) from liver and other sources


Investigating unexplained causes of LDH elevations


Detection of macro-LDH

Necessary Information

Patient's age is required.

Specimen Required

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

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

Collection Instructions: Centrifuge and aliquot serum into 2 plastic vials, each containing 1 mL, within 2 hours of collection.

Specimen Type


Specimen Minimum Volume

0.75 mL

Specimen Stability Information

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

Day(s) Performed

Monday, Wednesday, Friday

Seattle Children's Hospital Note:

TAT: 3 - 6 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Method Name

LDI: Electrophoresis Densitometry

LD: Photometric Rate Reaction

Method Description

Total Lactate Dehydrogenase:

Lactate and nicotinamide adenine dinucleotide (NAD[+]), in the presence of lactate dehydrogenase (LDH), 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: LDH reagent. Roche Diagnostics; 08/2019)



The 5 isoenzymes of LDH are separated by electrophoresis on agarose film. The serum samples are electrophoresed and separated LDH isoenzymes are visualized using a specific chromogenic substrate. The amount of resulting formazan precipitate is proportional to the LDH enzymatic activity. Densitometry is used to obtain relative quantification of each fraction. The fractions are numbered according to their electrophoretic mobility, LDH-I being the most mobile.(Tietz NW, ed. Clinical Guide to Laboratory Tests. 3rd ed. WB Saunders Company; 1995; package insert: Sebia Hydragel ISO-LDH. Sebia; 07/2019)

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, approved, or is exempt by the US 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



LOINC Code Information

Test ID Test Order Name Order LOINC Value
LD_I Lactate Dehydrogenase Isoenzymes, S 42929-0


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

Profile Information

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

Report Available

3 to 6 days

Reject Due To

Gross hemolysis Reject
Gross lipemia OK