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
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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 |