Summary & Overview
CPT 0107U: Singulex Clarity C. diff Toxins A/B Assay
CPT code 0107U designates a proprietary laboratory assay — the Singulex Clarity® C. diff toxins A/B test — that detects Clostridium difficile toxins A and B in stool using a rapid, multi‑step immunoassay. As a PLA CPT code, 0107U applies to a single, manufacturer‑specific diagnostic test and is used to report performance of this proprietary assay by the producing laboratory. Nationally, PLA codes matter because they identify and track use of unique commercial diagnostic technologies that can influence laboratory workflow, payer coverage decisions, and public health reporting for infectious diseases.
Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise briefing on the clinical purpose of the test, typical sites of service, and the scope of coverage considerations across major national payers. The publication summarizes benchmarks and policy context relevant to laboratory billing for proprietary assays, outlines common modifier usage where applicable, and provides clinical context for interpreting a positive or negative C. difficile toxin result. The content is intended to inform coding, billing, and payor policy teams, as well as laboratory administrators and clinicians involved in diagnostic strategy and test utilization.
Billing Code Overview
CPT code 0107U is a Proprietary Laboratory Analyses (PLA) code for the Singulex Clarity® C. diff toxins A/B assay by Singulex Labs. The code reports a rapid, highly sensitive, multi–step immunoassay performed on a stool specimen to detect the presence or absence of Clostridium difficile toxins A and B (TcdA and TcdB).
Service type: Laboratory infectious disease diagnostic test
Typical site of service: Clinical laboratory or reference laboratory; specimen collected in outpatient or inpatient settings and sent to the performing laboratory for analysis.
Clinical & Coding Specifications
Clinical Context
A hospitalized adult or outpatient presenting with acute onset of watery diarrhea, abdominal cramping, and recent antibiotic exposure undergoes stool testing to evaluate for Clostridioides difficile infection. A stool specimen is collected in a clean container and sent to the reference or hospital laboratory. The laboratory performs the Singulex Clarity® C. diff toxins A/B assay, a rapid, highly sensitive proprietary immunoassay that detects presence or absence of C. difficile toxins A (TcdA) and B (TcdB) in the stool. Results are reported as positive, negative, or indeterminate and documented in the patient’s chart. Clinical workflow steps include specimen collection, accessioning, test performance on the Singulex platform, result verification by a laboratory technologist, and result reporting to the ordering clinician. Typical sites of service are hospital inpatient laboratories, outpatient hospital labs, and independent specialty reference laboratories. The service type is a single-target laboratory diagnostic test (Proprietary Laboratory Analysis) specific to the manufacturer’s assay.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
00 | (Placeholder - not standard CMS) | Data not available in the input. |
11 | Office or other outpatient visit code (professional) | Use when reporting professional component if applicable to the billing arrangement. |
22 | Increased procedural services | Use when performance of the test requires substantially greater effort than usual. |
26 | Professional component | Use when billing only the professional component (interpretation/analysis) separate from technical component. |
52 | Reduced services | Use when the test is partially reduced or not fully performed. |
53 | Discontinued procedure | Use when test processing was started but discontinued for patient-related reasons. |
62 | Two surgeons | Use when two providers with different specialties share responsibility for test-related procedures (rare for lab tests). |
78 | Unplanned return to the operating/procedure room | Not typically used for this lab test; included for completeness if related procedure requires immediate repeat. |
80 | Assistant surgeon | Not typically applicable to laboratory testing; included when an assistant participates in a related procedure. |
82 | Assistant surgeon (when qualified resident not available) | As above, rarely applicable to this laboratory assay. |
AD | Medical supervision by a physician or other qualified health care professional | Use to indicate direct supervision arrangements when required. |
TC | Technical component | Use when billing only the technical component (labor, reagents, instrumentation) of the assay. |
QX | Service furnished under a CRNA’s supervision (modifier QX historically for anesthesia) | Generally not applicable; included only if specific payer instructions require it for non-standard billing. |
QY | Medical direction by one physician of two or more qualified individuals | Rarely applicable to laboratory testing but may apply to specialized reference lab oversight. |
| Taxonomy Code | Specialty | Notes |
|---|---|---|
| 2080P0207X | Clinical Pathology | Common specialty responsible for laboratory testing and result interpretation. |
| 207K00000X | Clinical Laboratory | Laboratory directors and supervisory personnel overseeing test performance. |
| 207L00000X | Medical Laboratory Technician | Personnel who perform the assay in hospital or reference labs. |
| 207RP1001X | Infectious Disease Specialist | Orders and interprets test in the context of patient management. |
| 2084P0800X | Gastroenterology | Clinicians who commonly request testing for diarrheal illness and suspected C. difficile. |
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|---|---|
A04.7 | Enterocolitis due to Clostridioides difficile | Primary indication for performing a C. difficile toxin assay to confirm active toxin-mediated disease. |
R19.7 | Diarrhea, unspecified | Common presenting symptom prompting stool testing for infectious causes including C. difficile. |
K52.9 | Noninfective gastroenteritis and colitis, unspecified | Differential diagnosis where toxin testing may be used to exclude C. difficile when infection is suspected. |
A09 | Infectious gastroenteritis and colitis, unspecified | Used when infectious etiology is suspected and testing for specific pathogens including C. difficile is performed. |
Z86.19 | Personal history of other infectious and parasitic diseases | Relevant for patients with prior C. difficile infection; clinicians may test for recurrence. |
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|---|---|
87045 | Culture, aerobic bacterial, with isolation and presumptive identification of isolates | Performed when culture-based methods are used alongside toxin testing to identify bacterial pathogens. |
87493 | Infectious agent antigen detection by immunoassay, qualitative or semiquantitative, multiple-step method; Clostridium difficile, toxin A or B | Alternative immunoassay method for C. difficile toxins; may be used instead of or in parallel with the Singulex assay. |
87496 | Infectious agent antigen detection by immunoassay, qualitative or semiquantitative, multiple-step method; Clostridium difficile, toxin A and B | Directly related antigen detection code for both toxins; often considered when ordering standard immunoassay panels. |
87802 | Infectious agent antigen detection by immunoassay, chromatographic method (e.g., lateral flow), qualitative or semiquantitative; Clostridium difficile | Rapid point-of-care tests that may be performed before or in conjunction with the Singulex laboratory assay. |
G0470 | Specimen handling and transport; per cc or per specimen (Medicare national) | Billing for specialized specimen handling or transport services related to processing stool specimens to reference labs. |