UnitedHealthcare’s March 1, 2026 revision to MMP391.16 adds and clarifies ICD code applicability for CPT 81335 (TPMT) testing, explicitly listing K50.00 (Crohn’s disease of small intestine without complications) alongside hematologic malignancy, transplant status, and autoimmune diagnosis codes. The excerpt is a code-only update—no clinical criteria, coverage limits, or rationale are provided. Several hematologic codes show past deletion effective dates (notably 07/12/2025), indicating prior temporal changes to the code list. Providers should use the updated code list when billing CPT 81335 but review full policy for any clinical or coverage guidance not included in this excerpt.
March 2026 Revision: Applicable Diagnosis Codes Added (includes Crohn's disease)
This revision lists the applicable diagnosis codes associated with pharmacogenomic testing for CPT 81335. The document includes several hematologic malignancy codes, rheumatologic and transplant status codes, and a gastrointestinal diagnosis: K50.00 (Crohn's disease of small intestine without complications). The policy text indicates that K50.00 is explicitly included alongside codes such as C91.00–C92.02, M06.89, M06.8A, Z94.0, and Z94.84.
No additional explanatory language, criteria, or coverage determinations beyond the list of applicable codes is provided in the excerpt. The effective date noted for the policy is 2026-03-01 (policy number MMP391.16), and specific deletion effective dates are shown for several leukemia codes (e.g., deleted 07/12/2025 for some C91.* codes).
`CPT 81335` (TPMT) Mapping to Specific ICD Codes
The policy excerpt centers on the applicability of (thiopurine S-methyltransferase [TPMT] testing) to a defined set of ICD diagnosis codes. The list pairs with multiple leukemia and lymphoid malignancy codes (, ), transplant status codes (, ), and inflammatory/rheumatologic codes (, ). Notably, (Crohn's disease of small intestine without complications) appears in this list, indicating that this gastrointestinal diagnosis is included among the codes applicable to in this policy text.
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