Test Catalog

Test Id : LDBF

Lactate Dehydrogenase (LDH), Body Fluid

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

Identification of exudative pleural effusions


Lactate dehydrogenase in pericardial fluids is not diagnostically useful.

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


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 (LD), BF

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

LD (Lactate Dehydrogenase), Body Fluids

LDH (Lactate Dehydrogenase), Body Fluids

Specimen Type
Describes the specimen type validated for testing

Body Fluid

Necessary Information

1. Date and time of collection are required.

2. Specimen source is required.


Question ID Description Answers
FLD11 Fluid Type, Lactate Dehydrogenase

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

Specimen Type: Body fluid

Preferred Source:

-Peritoneal fluid (peritoneal, abdominal, ascites, paracentesis)

-Pleural fluid (pleural, chest, thoracentesis)

-Drain fluid (drainage, JP drain)



-Cerebral spinal fluid

Acceptable Source: Write in source name with source location (if appropriate)

Collection Container/Tube: Sterile container

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Centrifuge to remove any cellular material and transfer into a plastic vial.

2. Indicate the specimen source and source location on label.

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

0.5 mL

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

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject
Anticoagulant or additive, Breast milk, nasal secretions, gastric secretions, bronchoalveolar lavage (BAL) or bronchial washings, colostomy/ostomy, feces,  saliva, sputum, urine, or vitreous fluid Reject

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
Body Fluid Ambient (preferred) 7 days
Refrigerated 48 hours

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

Identification of exudative pleural effusions


Lactate dehydrogenase in pericardial fluids is not diagnostically useful.

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

Lactate dehydrogenase (LDH) activity is present in all cells of the body with the highest concentrations in the heart, liver, muscle, kidney, lung, and erythrocytes.


Pleural fluid:

Pleural fluid is normally present within the pleural cavity surrounding the lungs, serving as a lubricant between the lungs and inner chest wall. Pleural effusion develops when the pleural cavity experiences an overproduction of fluid due to increased capillary hydrostatic and osmotic pressure that exceeds the ability of the lymphatic or venous system to return the fluid to circulation. Laboratory-based criteria are often used to classify pleural effusions as either exudative or transudative. Exudative effusions form due to infection or inflammation of the capillary membranes allowing excess fluid into the pleural cavity. Patients with these conditions benefit from further investigation and treatment of the local cause of inflammation. Transudative effusions form due to systemic conditions such as volume overload, end stage kidney disease, and heart failure that can lead to excess fluid accumulation in the pleural cavity. Patients with transudative effusions benefit from treatment of the underlying condition.(1) Measurement of LDH in body fluids is primarily indicated to aid in the differentiation of transudative and exudative effusions as LDH activity is considered an indicator of the extent of inflammation. Dr. Richard Light derived criteria in the 1970s for patients with pleural effusions that are still used today.(2)


The criteria include the measurement of total protein and LDH in pleural fluid and serum. Exudates are defined as meeting one of the following criteria:

1. Pleural fluid-to-serum protein ratio above 0.5

2. Pleural fluid LDH above two-thirds the upper limit of normal serum LDH

3. Pleural fluid-to-serum LDH ratio above 0.6


Pericardial fluid:

The routine analysis of LDH to differentiate exudative and transudative pericardial effusions is not considered helpful.(3)


Peritoneal fluid:

Spontaneous bacterial peritonitis or ascitic fluid infection is common (12%) at the time of admission of a patient with cirrhosis and ascites. The diagnosis is made in the presence of an elevated ascitic fluid absolute polymorphonuclear (PMN) leukocyte count (ie, >250 cells/mm(3) [0.25 x 10(9)/L]) without an evident intra-abdominal, surgically treatable source of infection.(4)


Secondary bacterial peritonitis (ie, ascitic fluid infection caused by a surgically treatable intra-abdominal source) can masquerade as spontaneous bacterial peritonitis. Signs and symptoms do not help separate patients who need surgical intervention from those who have spontaneous bacterial peritonitis and need only antibiotic treatment. In contrast, the initial ascitic fluid analysis and the response to treatment can assist with this important distinction. The characteristic analysis in the setting of free perforation is PMN count of 250 cells/mm(3) (usually many thousands) or higher, multiple organisms (frequently including fungi and enterococcus) on Gram stain and culture, and at least 2 of the following criteria: total protein above 1 g/dL, LDH above the upper limit of normal for serum, and glucose below 50 mg/dL. Studies have reported higher than 95% sensitivity but low specificity using these criteria; a computerized tomographic scan was diagnostic in 85% of patients with secondary peritonitis.(5)

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.

An interpretive report will be provided.

Provides information to assist in interpretation of the test results

Pleural fluid lactate dehydrogenase (LDH) to serum LDH ratio above 0.6 are most consistent with exudative effusions.(2,6)


Peritoneal fluid LDH above 220 U/L suggests secondary, rather than spontaneous bacterial peritonitis, in conjunction with other laboratory, imaging, and clinical findings.(4,5)


Synovial fluid LDH may be elevated greater than plasma or serum LDH due to inflammatory causes. Values should be interpreted in conjunction with other clinical findings.(7)


All other fluids: LDH may be used to differentiate transudative from exudative effusions. The decision limits are not well defined in fluids other than pleural fluid and should be interpreted in conjunction with other clinical findings.

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

Lactate dehydrogenase (LDH) activity is one of the most sensitive indicators of in vitro hemolysis. Causes can include transportation via pneumatic tube and vigorous mixing.


Contamination with erythrocytes will elevate results, because the analyte level in erythrocytes is higher than in normal sera. The level of interference may be variable depending on the content of analyte in the lysed erythrocytes.


In very rare cases of gammopathy, in particular Waldenstrom macroglobulinemia, type IgM, may cause unreliable results.

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

1. Block DR, Florkowski CM: Body fluids. In: Rifai N, Horvath AR, Wittwer CT. eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:chap 43

2. Light RW, Macgregor I, Luchsinger PC, Ball WC: Pleural effusions: the diagnostic separation of transudates and exudates. Ann Intern Med. 1972;77:507-513

3. Ben-Horin S, Bank I, Shinfeld A, et al: Diagnostic value of the biochemical composition of pericardial effusions in patients undergoing pericardiocentesis. Am J Cardiol. 2007;99(9):1294-1297

4. Soriano G, Castellote J, Alvarez C, et al: Secondary bacterial peritonitis in cirrhosis: a retrospective study of clinical and analytical characteristics, diagnosis and management. J Hepatol. 2010 Jan;52(1):39-44

5. Sahn, SA: Getting the most from pleural fluid analysis. Respirology. 2012;17:270-277

6. Tarn AC, Lapworth R: Biochemical analysis of ascitic (peritoneal) fluid: what should we measure? Ann Clin Biochem. 2010;47:397-407

7. Pejovic M, Stankovic A, Mitrovic DR: Lactate dehydrogenase activity and its isoenzymes in serum and synovial fluid of patients with rheumatoid arthritis and osteoarthritis. J Rheumatol. 1992;19:529-533

8. Nandakumar V, Dolan C, Baumann NA, et al: Effect of pH on the quantification of body fluid analytes for clinical diagnostic testing. Am J Clin Path. 2019 Oct; 152(1):S10-S11

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

Lactate and nicotinamide adenine dinucleotide, in the presence of lactate dehydrogenase, are converted to pyruvate and NADH. The rate at which NADH is formed is determined by increase in absorbance and is directly proportional to enzyme activity.(Package insert: Roche LDH reagent. Roche Diagnostics; V12.0 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 through Sunday

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.

Same day/1 to 2 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


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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 modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

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
LDBF Lactate Dehydrogenase (LD), BF 14803-1
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_BF Lactate Dehydrogenase (LD), BF 14803-1
FLD11 Fluid Type, Lactate Dehydrogenase 14725-6

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