Summary & Overview
CPT 0077U: M-Protein Detection and Isotyping by MALDI-TOF
CPT code 0077U is a Proprietary Laboratory Analyses (PLA) code for the Mayo Clinic Laboratory’s M–Protein Detection and Isotyping by MALDI–TOF Mass Spectrometry. The assay isolates and identifies monoclonal (M–) proteins in patient specimens to aid diagnosis of monoclonal gammopathy. PLA codes like 0077U are important nationally because they designate single-source, manufacturer- or lab-specific tests that can influence laboratory billing, coverage determinations, and access to specialty diagnostics.
Key payers addressed in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical purpose and typical use settings, a summary of payer coverage themes, and benchmarks where available. The publication outlines coding context, common modifiers used with proprietary laboratory codes, and implications for laboratory service lines and referring clinicians. It also highlights areas where payers commonly require clinical documentation or prior authorization for single-source laboratory assays. Where input data is missing, the publication notes that specific items are not available in the source information.
Billing Code Overview
CPT code 0077U is a Proprietary Laboratory Analyses (PLA) code for M–Protein Detection and Isotyping by MALDI–TOF Mass Spectrometry, developed by the Mayo Clinic Laboratory. The test isolates and identifies monoclonal (M–) proteins in a patient specimen to aid in diagnosing monoclonal gammopathy, a condition characterized by abnormal proteins in the blood.
Service Type: Laboratory — Proprietary diagnostic assay using mass spectrometry
Typical Site of Service: Clinical laboratory or reference laboratory setting
Data not available in the input.
Clinical & Coding Specifications
Clinical Context
A 67-year-old male with unexplained anemia and hypercalcemia is referred by his hematologist for laboratory evaluation of a suspected monoclonal gammopathy. The patient presents for routine phlebotomy at an outpatient hospital laboratory. The ordering clinician requests M–Protein Detection and Isotyping by MALDI–TOF Mass Spectrometry, reported under code 0077U, to isolate and identify monoclonal (M–) proteins in the serum sample to aid in diagnosis and isotype classification (for example, IgG kappa, IgA lambda). The clinical workflow: the clinician orders the test in the electronic medical record, the specimen (serum) is collected, labeled, and sent to the Mayo Clinic Laboratory or the performing proprietary laboratory. The specimen is processed and analyzed using MALDI–TOF mass spectrometry. Results returned to the ordering clinician include detection of an M–protein and its isotype, which informs further diagnostic steps such as bone marrow biopsy, serum immunofixation, serum free light chain testing, imaging, or hematology referral. Typical site of service is an outpatient clinical laboratory or hospital laboratory with referral to the proprietary testing laboratory when required. The service type is a specialized laboratory diagnostic test (Proprietary Laboratory Analysis) performed on blood/serum for protein characterization in suspected monoclonal gammopathy.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
90 | Reference (Outside) Laboratory | Use when the test is performed by an outside/reference laboratory (e.g., Mayo Clinic Laboratory) and results are reported to the ordering provider. |
91 | Repeat Clinical Diagnostic Lab Test | Use when a repeat specimen is analyzed and reporting separate result is required for serial monitoring within the same encounter. |
26 | Professional Component | Use if billing is separated and the professional interpretation component is billed separately from the technical component. |
TC | Technical Component | Use when billing for the technical component only (laboratory processing and analysis) separate from professional interpretation. |
90 | Reference (Outside) Laboratory | Use when sending specimen to an external proprietary lab (duplicate entry acknowledges frequent use for PLA tests). |
59 | Distinct Procedural Service | Use when this PLA is reported with other laboratory procedures on the same date that are normally bundled, and documentation supports a distinct service. |
52 | Reduced Services | Use when full testing cannot be performed and a reduced scope of the test is reported. |
53 | Discontinued Procedure | Use if specimen collection or testing was started but discontinued for documented clinical reasons. |
22 | Increased Procedural Services | Use when reporting that this test required substantially greater resources or complexity compared with the usual service. |
90 | Reference (Outside) Laboratory | Use when the performing lab is an external specialty/reference lab (listed due to high relevance for PLA code logistics). |
| Taxonomy Code | Specialty | Notes |
|---|---|---|
| 2080P0206X | Pathology | Clinical pathology and laboratory medicine specialists oversee test interpretation and laboratory operations for specialized mass spectrometry assays. |
| 207RP1001X | Hematology | Hematologists order and interpret results for monoclonal gammopathy evaluation and downstream management. |
| 208000000X | Clinical Laboratory | Medical technologists and laboratory directors manage specimen processing and technical performance of MALDI–TOF assays. |
| 363L00000X | Laboratory Director | Individuals with laboratory directorship responsibilities for regulatory and quality oversight of proprietary assays. |
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|---|---|
D47.2 | Monoclonal gammopathy of undetermined significance (MGUS) | Primary diagnosis indicating presence of M–protein without end-organ damage; this test identifies and types the monoclonal protein. |
C90.00 | Multiple myeloma not having achieved remission | Malignant plasma cell disorder where M–protein detection and isotyping guide diagnosis and monitoring. |
C90.01 | Multiple myeloma in remission | Used when monitoring for residual or recurrent M–protein after treatment. |
R79.89 | Other specified abnormal findings of blood chemistry | Non-specific abnormal lab findings prompting protein characterization with M–protein testing. |
D89.83 | Monoclonal gammopathy associated with peripheral neuropathy | Clinical scenario where identifying M–protein type aids in etiologic assessment of neuropathy. |
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|---|---|
80055 | General health panel; includes calcium and other chemistries | Performed before or alongside to evaluate hypercalcemia and renal function in suspected monoclonal gammopathy. |
84165 | Immunoglobulin quantification; serum | Provides quantitative immunoglobulin levels (IgG, IgA, IgM) that complement M–protein detection and isotyping. |
86336 | Immunoassay for infectious agent antibody(ies) or antigen(s), qualitative or semiquantitative, single step | Represents standard immunoassay methods; may be performed in parallel laboratories for differential testing (note: used generically for related serologic assays). |
84402 | Thyroid stimulating hormone (TSH) | Example of common concurrent laboratory testing in broad diagnostic workups of older adults (clinical workflow adjunct). |
85025 | Complete blood count (CBC) with automated differential | Frequently ordered to evaluate anemia and other hematologic abnormalities that prompt monoclonal protein testing. |