E06.5
BillableOther chronic thyroiditis
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is E06.5 an HCC code?
No. E06.5 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for E06.5
For E06.5to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed E06.5 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
E06.5 is the ICD-10-CM diagnosis code for other chronic thyroiditis. Chronic inflammation of the thyroid gland due to causes other than autoimmune, drug-induced, or transient thyrotoxicosis forms. E06.5 sits in the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89), within the section covering disorders of thyroid gland (e00-e07).
E06.5 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Maps to RxHCC 44 (Osteoporosis, Vertebral and Pathological Fractures) in the prescription drug model. This code does not map to CMS-HCC v28 or v24 models. The RxHCC mapping supports risk adjustment for the medication costs associated with thyroid hormone replacement and potentially immunosuppressive therapy.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E06.5 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only after excluding autoimmune, drug-induced, and other specified chronic thyroiditis types
- •Document the underlying etiology if identifiable (radiation, infiltrative disease, etc.)
Clinical Significance
Other chronic thyroiditis includes chronic fibrous thyroiditis (Riedel's thyroiditis) and other non-autoimmune chronic inflammatory thyroid conditions. Riedel's thyroiditis is extremely rare, characterized by dense fibrosis replacing normal thyroid tissue and potentially extending into surrounding neck structures, which can cause compressive symptoms including dysphagia, stridor, and recurrent laryngeal nerve palsy. This condition may be part of IgG4-related disease.
Documentation Requirements
- ✓Document the specific type of chronic thyroiditis, histologic findings if available, imaging characteristics demonstrating fibrosis or chronic inflammation, thyroid function status, and any compressive symptoms.
- ✓For Riedel's thyroiditis, note the extent of fibrosis beyond the thyroid capsule and IgG4 levels if tested.
Commonly Confused Codes
- •
- •
- •