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Official Description

Lactate dehydrogenase (LD), (LDH); isoenzymes, separation and quantitation

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

The CPT® Code 83625 refers to the laboratory test for lactate dehydrogenase (LD) isoenzymes, specifically focusing on their separation and quantitation. Lactate dehydrogenase (LDH) is an important enzyme that plays a critical role in the metabolic process, particularly in the conversion of lactate to pyruvate. This enzyme is found in various tissues throughout the body, including red blood cells (RBCs), heart, liver, pancreas, kidneys, skeletal muscle, brain, and lungs. The presence of LDH in these tissues means that it can serve as a valuable biomarker for tissue damage or disease. LDH exists in five distinct isoenzymes, each with a unique structure and distribution across different organs. These isoenzymes are categorized as LDH-1, LDH-2, LDH-3, LDH-4, and LDH-5. LDH-1 is predominantly located in heart muscle and red blood cells, making it particularly relevant in diagnosing cardiac conditions. LDH-2 is primarily found in white blood cells, while LDH-3 is associated with lung tissue. LDH-4 is present in the kidney, placenta, and pancreas, and LDH-5 is mainly found in the liver and skeletal muscle. By measuring the levels of these specific LDH isoenzymes, healthcare providers can gain insights into the location and extent of tissue damage, which can aid in diagnosing various medical conditions. The test is performed by obtaining a blood sample through venipuncture, and the serum is then analyzed using quantitative enzymatic methodology and electrophoresis to separate and quantify each isoenzyme individually.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The lactate dehydrogenase (LDH) isoenzyme test, represented by CPT® Code 83625, is indicated for various clinical scenarios where tissue damage or disease is suspected. The following conditions may warrant this test:

  • Myocardial Infarction The test can help in diagnosing heart attacks by measuring elevated levels of LDH-1, which is primarily found in heart muscle.
  • Hemolytic Anemia Elevated LDH levels may indicate the destruction of red blood cells, making this test useful in diagnosing hemolytic conditions.
  • Liver Disease LDH-5 is associated with liver tissue; thus, increased levels may suggest liver damage or disease.
  • Muscle Disorders Conditions affecting skeletal muscle may lead to elevated LDH-5 levels, indicating muscle injury or disease.
  • Malignancies Certain cancers can cause elevated LDH levels, making this test a useful marker in oncology.

2. Procedure

The procedure for conducting the lactate dehydrogenase isoenzyme test involves several key steps to ensure accurate results. First, a blood sample is obtained from the patient through a process known as venipuncture. This involves inserting a needle into a vein, typically in the arm, to collect the necessary blood volume. The blood sample is then placed in a suitable container for serum separation.

  • Sample Collection The healthcare professional performs venipuncture to draw blood, which is then collected in a tube that allows for serum separation.
  • Serum Separation After collection, the blood sample is centrifuged to separate the serum from the cellular components. This step is crucial as the serum contains the LDH isoenzymes that will be analyzed.
  • Quantitative Analysis The serum is subjected to quantitative enzymatic methodology and electrophoresis. This process involves using specific reagents to measure the activity of LDH and separate the isoenzymes based on their charge and size.
  • Isoenzyme Quantification Each isoenzyme (LDH-1 through LDH-5) is quantified individually, allowing for a detailed analysis of the levels present in the serum. This quantification is essential for determining the source of tissue damage.

3. Post-Procedure

After the lactate dehydrogenase isoenzyme test is completed, the patient may experience minimal discomfort at the venipuncture site, which typically resolves quickly. There are no specific post-procedure care instructions required for this test, as it is a routine laboratory procedure. However, healthcare providers may advise patients to monitor the site for any unusual swelling or bruising. The results of the test will be analyzed and interpreted by a qualified healthcare professional, who will discuss the findings with the patient and determine any necessary follow-up actions based on the isoenzyme levels detected.

Short Descr ASSAY OF LDH ENZYMES
Medium Descr LACTATE DEHYDROGENASE ISOENZYMES SEP&QUAN
Long Descr Lactate dehydrogenase (LD), (LDH); isoenzymes, separation and quantitation
Status Code Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC) 9 - Not Applicable
Multiple Procedures (51) 9 - Concept does not apply.
Bilateral Surgery (50) 9 - Concept does not apply.
Physician Supervisions 09 - Concept does not apply.
Assistant Surgeon (80, 82) 9 - Concept does not apply.
Co-Surgeons (62) 9 - Concept does not apply.
Team Surgery (66) 9 - Concept does not apply.
Diagnostic Imaging Family 99 - Concept Does Not Apply
CLIA Waived (QW) No
APC Status Indicator Conditionally packaged laboratory tests
Type of Service (TOS) 5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS) T1H - Lab tests - other (non-Medicare fee schedule)
MUE 1
CCS Clinical Classification 233 - Laboratory - Chemistry and Hematology
90 Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number.
59 Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25.
GA Waiver of liability statement issued as required by payer policy, individual case
GW Service not related to the hospice patient's terminal condition
GY Item or service statutorily excluded, does not meet the definition of any medicare benefit or, for non-medicare insurers, is not a contract benefit
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