Microsatellite Instability Analysis

CPT: 81301; 88381
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Test Details


  • Colorectal Cancer Screening
  • Hereditary Nonpolyposis Colorectal Cancer, Screening
  • Mismatch Repair Defect
  • Replication Repair (RER)


Identify tumors with microsatellite instability. High-frequency microsatellite instability (MSI-H) is associated with Lynch syndrome, but it is also found in 15% to 20% of sporadic colorectal and endometrial cancers. Lynch syndrome is an autosomal-dominant inherited cancer syndrome that predisposes to colorectal, endometrial, gastric, ovarian, upper urinary tract, and other cancers.


MSI-H is a marker of underlying DNA mismatch repair defect but does not define specific gene mutations responsible for cancers. If direct testing for gene mutations responsible for Lynch syndrome is desired, please call customer service at 800-345-4363 for more information. This assay can detect 8% to 12% of mutant in a background of wild-type genomic DNA.

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).


Multiplex polymerase chain reaction (PCR); capillary electrophoresis

Specimen Requirements


One paraffin-embedded tumor and either whole blood or paraffin-embedded normal tissue


Eight unstained slides at 5 μM and one matching H&E slide or FFPE tissue block or 3-5 mL whole blood

Minimum Volume

Samples with ≥4 mm² tumor and normal tissue surface area and ≥50% tumor content are preferred.


FFPE tissue block or slides, lavender-top (EDTA) tube, or green-top (sodium heparin) tube

Storage Instructions

Blocks and slides at room temperature; whole blood at 2°C to 8°C

Causes for Rejection

Tumor block containing insufficient tumor tissue or no tumor; broken or stained slides. Whole blood: Contaminated specimen; frozen whole blood received; leaking tube; clotted blood; hemolysis; specimen containing suspicious foreign material; quantity not sufficient for analysis

Clinical Information

Special Instructions

This assay needs both (1) DNA prepared from FFPE (formalin-fixed and paraffin-embedded) tumor tissue and (2) matched normal tissue (FFPE or blood). Please provide a copy of the pathology report. This test will be delayed if the pathology report is not received. Please direct any questions regarding this test to customer service at 800-345-4363.


NCCN Clinical Practice Guidelines in Oncology: Genetic/Familial High-Risk Assessment: Colorectal. Version 2.2015.
Promega Technical Manual. MSI Analysis System v1.2. Oct 2012.


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
511855 Microsatellite Instability 511856 Results: 43368-0
511855 Microsatellite Instability 511857 Indications: 55752-0
511855 Microsatellite Instability 511859 Specimen Location: 31208-2
511855 Microsatellite Instability 511860 Specimen Type: 66746-9
511855 Microsatellite Instability 511861 Block Number: N/A
511855 Microsatellite Instability 511862 Background: 77202-0
511855 Microsatellite Instability 511863 Methodology: 49549-9
511855 Microsatellite Instability 511864 References: 75608-0
511855 Microsatellite Instability 511865 Director Review: 72486-4
511855 Microsatellite Instability 480903 Microdissection Performed 8100-0

For Providers

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CPT Statement/Profile Statement

The LOINC® codes are copyright © 1994-2018, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf