Summary & Overview

CPT 0169U: NUDT15 and TPMT Genotyping Panel

CPT code 0169U designates a Proprietary Laboratory Analyses (PLA) genotyping panel from RPRD Diagnostics that assesses common variants in the NUDT15 and TPMT genes. These genetic markers influence patient response and risk of toxicity to thiopurine drugs, which are used broadly in oncology (notably acute lymphoblastic leukemia), gastroenterology (inflammatory bowel disease), and transplant medicine. Nationwide, precise genotyping supports safer prescribing and personalized dosing, reducing adverse drug reactions and improving treatment outcomes.

Key payers reviewed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a focused overview of clinical context for the test, typical sites of service, and the types of stakeholders likely to engage with this PLA-coded assay. The publication provides benchmarks and payer coverage patterns where available, clarifies the code’s role in billing workflows, and summarizes recent policy and coding considerations relevant to proprietary laboratory analyses. The content is intended to help clinicians, laboratory managers, and revenue cycle professionals understand the clinical purpose of the assay, common billing contexts, and what information is typically needed for payer adjudication. Data not provided in the input (for example, associated taxonomies, specific ICD-10 diagnoses, or related CPT/HCPCS codes) is noted as unavailable.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare0169UCPTProprietary Laboratory AnalysesGenotypingNUDT15TPMTThiopurine PharmacogeneticsMolecular Diagnostics

Billing Code Overview

CPT code 0169U is a Proprietary Laboratory Analyses (PLA) code that applies to a single, vendor-specific genetic test. Report 0169U for the NT (NUDT15 and TPMT) genotyping panel from RPRD Diagnostics. The test evaluates common variants in the NUDT15 and TPMT genes that can affect toxicity and dosing of thiopurine medications used in conditions such as acute lymphoblastic leukemia (ALL), inflammatory bowel disease (IBD), and organ transplant rejection.

Service Type: Genetic / molecular diagnostic testing (genotyping panel)

Typical Site of Service: Clinical laboratory or specialized molecular diagnostics facility

Data not available in the input for associated taxonomies, ICD-10 diagnoses, and related codes.

Clinical & Coding Specifications

Clinical Context

A 12-year-old patient with newly diagnosed acute lymphoblastic leukemia (ALL) is scheduled to begin maintenance therapy that includes thiopurine drugs (e.g., mercaptopurine). The oncology team orders the NT (NUDT15 and TPMT) genotyping panel (0169U) from RPRD Diagnostics prior to initiating thiopurine therapy to identify common variants that affect drug metabolism and risk of severe myelosuppression. Peripheral blood is collected in an appropriate EDTA tube during a routine clinic visit or hospital admission and sent to the reference laboratory. The laboratory performs targeted genotyping of NUDT15 and TPMT variants and reports results as genotype and interpreted phenotype (e.g., normal, intermediate, or poor metabolizer) with dosing implications and risk of toxicity. The molecular test result is reviewed by the treating oncologist or gastroenterologist, documented in the electronic health record, and used to guide initial thiopurine dosing and monitoring plan. Typical sites of service include outpatient oncology clinics, pediatric hematology clinics, inpatient hospital units, and specialty infusion or transplant clinics. The service type is a laboratory molecular/genetic diagnostic test (Proprietary Laboratory Analyses/PLA).

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when reporting only the professional (interpretation) component if the laboratory separates technical and professional services and a billing entity provides interpretation.
`TC`	Technical component	Use when reporting only the technical component for the lab performing specimen processing and analysis.
`59`	Data not available in the input.	Data not available in the input.
`76`	Data not available in the input.	Data not available in the input.
`77`	Data not available in the input.	Data not available in the input.
`80`	Assistant surgeon	Use when a qualified assistant participates in specimen collection or procedures requiring surgical assistance related to sample acquisition.
`62`	Two surgeons	Use when two surgeons of different specialties are required for a procedure to obtain sample (rare for peripheral blood draws; applicable if complex biopsy is performed).
`52`	Reduced services	Use when the laboratory or provider performs a reduced service compared with the full test (e.g., partial panel performed).
`53`	Discontinued procedure	Use if specimen collection or testing was started but discontinued for clinical reasons before completion.
`AD`	Advanced beneficiary notice on file (Medicare)	Use when an ABN is documented and the beneficiary may be financially liable for the test.
`QX`	Ordering physician is not the performing physician (CLIA QX)	Use when the ordering clinician is different from the performing laboratory and CLIA regulations require reporting this modifier.
`QK`	Physician absence, test performed by non-physician practitioner	Use when the professional component is performed by an advanced practice clinician where payer accepts `QK`.
`QY`	Laboratory test performed at a separate entity (CLIA)	Use when a separate laboratory performs the test under CLIA and reporting must indicate external performance.
`SH`	Physician/other qualified health care professional services in a skilled nursing facility	Use when the ordering or interpreting clinician documents services provided in a skilled nursing facility setting.

Taxonomy Code	Specialty	Notes
207RC0000X	Pediatric Hematology-Oncology	Common ordering specialty for pediatric ALL patients and thiopurine use.
207RG0100X	Medical Oncology	Orders genotyping for cancer-related thiopurine therapy and dosing.
207RH0002X	Gastroenterology	Orders testing for inflammatory bowel disease patients requiring thiopurines.
3336C0006X	Clinical Laboratory	Performing laboratory specialty for genetic/molecular testing.
2080P0208X	Transplant Hepatology	Orders testing in transplant recipients when thiopurines are considered for immunosuppression or concomitant therapy.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`C91.0`	Acute lymphoblastic leukemia	ALL is a primary indication for thiopurine therapy where NUDT15/TPMT genotyping guides dosing to prevent myelosuppression.
`K50.90`	Crohn disease, unspecified, without complications	Crohn disease is treated with thiopurines such as azathioprine or mercaptopurine; genotyping predicts toxicity risk.
`K51.90`	Ulcerative colitis, unspecified, without complications	Ulcerative colitis patients may receive thiopurines; testing informs safe dosing.
`T86.19`	Other complication of kidney transplant	Post-transplant immunosuppression regimens sometimes include thiopurines; genotyping aids risk assessment.
`Z92.241`	Personal history of antineoplastic chemotherapy	Used in medication history documentation where prior chemotherapy and thiopurine exposure inform testing and management.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`36415`	Collection of venous blood by venipuncture	Used to obtain the blood specimen for the genotyping test prior to sending to the reference laboratory.
`81025`	Urine pregnancy test, non-automated, qualitative, single step method (e.g., for females of childbearing potential prior to chemotherapy)	Performed in some workflows to confirm pregnancy status before initiating cytotoxic therapy that may include thiopurines.
`86337`	Immunoassay for infectious agent antibody(ies) (e.g., hepatitis B, hepatitis C)	Performed in pre-treatment infectious disease screening panels that often accompany oncology or transplant workups; may occur concurrently with genetic testing.
`81225`	NUDT15 (if available in broader molecular series) — Data not available in the input.	Data not available in the input.
`81355`	TPMT (if available in broader molecular series) — Data not available in the input.	Data not available in the input.
`0001U`	Data not available in the input.	Data not available in the input.