Test Catalog

Test Id : LD_I

Lactate Dehydrogenase (LDH) Isoenzymes, Serum

Useful For
Suggests clinical disorders or settings where the test may be helpful

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

Profile Information
A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.

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

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

LDI: Electrophoresis Densitometry

LD: Photometric Rate Reaction

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Lactate Dehydrogenase Isoenzymes, S

Lists additional common names for a test, as an aid in searching

Isoenzymes of Lactate Dehydrogenase (LD)

Lactate Dehydrogenase Isoenzymes, S

LD (Lactate Dehydrogenase)

LD Isoenzymes

LDH (Lactate Dehydrogenase)

LDH Fractionation

LDH Isoenzymes

Specimen Type
Describes the specimen type validated for testing


Necessary Information

Patient's age is required.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

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.

Special Instructions
Library of PDFs including pertinent information and forms related to the test


Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.75 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia OK

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

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

Useful For
Suggests clinical disorders or settings where the test may be helpful

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

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Lactate dehydrogenase (LDH) is a tetrameric cytoplasmic enzyme present in all cells of the body with highest concentrations in heart, liver, muscle, kidney, lung, and erythrocytes. As with other proteins used as tissue-function markers, the appearance of LDH in the serum occurs only after prolonged hypoxia and is elevated in a number of clinical conditions, including cardiorespiratory diseases, malignancy, hemolysis, and disorders of the liver, kidneys, lung, and muscle.


. LDH exhibits 5 isomeric forms composed of H (heart) and M (muscle) subunits. The isoenzyme designation usually is LDH-I (H4), LDH-II (H3M), LDH-III (H2M2), LDH-IV (HM3), and LDH-V (M4). Each isoenzyme is differentially expressed in various tissues, which forms the basis of its importance as a diagnostic marker. For example, heart muscle cells preferentially synthesize H subunits, while liver cells synthesize M subunits nearly exclusively. Skeletal muscle synthesizes largely M subunits; therefore LDH-V is both a liver and skeletal muscle form of LDH. The LDH-I and LDH-V forms are most often used to indicate heart or liver pathology, respectively.


LDH-I appears elevated in the serum about 24 to 48 hours after a myocardial infarction (MI), though generally, it is not as useful as troponin for detection of MI, unless the MI occurred at least 24 hours prior to testing. Normally, LDH-II is greater than LDH-I; however, when an MI has occurred, there is a "flip" in the ratio of LDH-I/LDH-II from less than 1 to greater than 1 (or at least >0.9). Use of the ratio for evaluation of patients with possible cardiovascular injury has largely been replaced by troponin testing (TRPS / Troponin T, 5th Generation, Plasma).


The LDH-V form is pronounced in patients with either primary liver disease or liver hypoxia secondary to decreased perfusion, such as occurs following an MI. However, LDH-V is usually not as reliable as the transaminases (eg, aspartate aminotransferase, alanine aminotransferase) for evaluating liver function. LDH-V also may be elevated in muscular damage and diseases of the skin.


Although it does not appear to cause or be associated with any symptoms or particular diseases, the presence of macro-LDH (LDH combined with an immunoglobulin) can cause an idiosyncratic elevation of total LDH.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.


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

> or =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%

Provides information to assist in interpretation of the test results

Marked elevations in lactate dehydrogenase (LDH) activity can be observed in megaloblastic anemia, untreated pernicious anemia, Hodgkin disease, abdominal and lung cancers, severe shock, and hypoxia.


Moderate-to-slight increases in LDH 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 kidney disease.


In liver disease, elevations of LDH are not as great as the increases in aspartate aminotransferase and alanine aminotransferase.


Increased levels of the enzyme are found in about one-third of patients with kidney disease, especially those with tubular necrosis or pyelonephritis. However, these elevations do not correlate well with proteinuria or other parameters of kidney disease.


On occasion, a raised LDH level may be the only evidence to suggest the presence of a hidden pulmonary embolus.


LDH-II is found in myocardium. Following a severe MI, the diagnostic ratio of LDH-I divided by LDH-II will change from less than 0.9 to greater than 0.9. This is referred to as an LDH "flip".


LDH-I elevation not due to myocardial damage may indicate hemolytic disease or other forms of in vivo hemolysis.


Elevation of LDH-V (least mobile isoenzyme) usually denotes liver damage. It is rarely helpful in defining skeletal muscle disease.


Macro-LDH can occur, which results in an elevation of LDH for no clinical reason. Macro-LDH greatly affects the migration of LDH isoenzymes since the addition of an immunoglobulin molecule greatly retards the migration of the usual LDH isoenzymes. If macro-LDH is present, the electrophoretogram will show atypically migrating isoenzymes with LDH activity localized near the origin.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

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


Testing should be used with caution in patients with chronic hemolytic anemias such as sickle cell disease as LDH levels may be falsely elevated due to their clinical status.


Freezing or prolonged storage at 4 degrees C (>12 hours) causes LDH-V to be lost.


Elevations of intermediate forms, LDH-II through LDH-IV, are rarely used to define a tissue of origin and such reports are largely anecdotal.


While increases in serum LDH also are seen following a myocardial infarction, the test has been replaced by the determination of troponin (TRPS / Troponin T, 5th Generation, Plasma).

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Panteghini M, Bais R: Serum enzymes. In: Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:407-431

2. Berridge BR, Herman E: In: Haschek and Rousseaux's Handbook of Toxicologic Pathology. 3rd ed. 2013

3. Farhana A, Lappin SL: Biochemistry, Lactate Dehydrogenase. In: StatPearls [Internet]. StatPearls Publishing; 2022. Updated May 8, 2022. Accessed September 7, 2022. Available at www.ncbi.nlm.nih.gov/books/NBK557536/

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

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)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday, Wednesday, Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

3 to 6 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

1 week

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

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  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.



LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
LD_I Lactate Dehydrogenase Isoenzymes, S 42929-0
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
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

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports