E06.5 ICD-10-CM Code: Other chronic thyroiditis
E06.5 is not a CMS-HCC payment code. MEAT criteria · RAF calculator · HCC Buddy coding tools
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FY 2026 Apr update / Endocrine, nutritional and metabolic diseases (E00-E89) / Disorders of thyroid gland (E00-E07)
E06.5
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceOther chronic thyroiditis
Chronic inflammation of the thyroid gland due to causes other than autoimmune, drug-induced, or transient thyrotoxicosis forms.
Buddy Insight
Other chronic thyroiditis includes chronic fibrous thyroiditis (Riedel's thyroiditis) and other non-autoimmune chronic inflammatory thyroid conditions.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
MappedHCC 44
RAF 0.070
Code Book Path
Inclusion Terms
Official- Chronic fibrous thyroiditis
- Chronic thyroiditis NOS
- Ligneous thyroiditis
- Riedel thyroiditis
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for E06.5 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for E06.5 in this effective period.
Excludes 1
Official- postpartum thyroiditis (O90.5)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for E06.5 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for E06.5 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for E06.5 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is E06.5 an HCC code?
E06.5 is not in the CMS-HCC V28 or V24 community payment model, but it does map to Thyroid and Parathyroid Disorders under the Part D RxHCC model.
- Code
- E06.5
- Description
- Other chronic thyroiditis
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF
- —
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. 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.
Work E06.5 in the Code Book — tabular path, V28 RAF, and MEAT checklist →
MEAT Criteria for E06.5
For E06.5 to 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.
Coder workflow notes
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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.
This code does not map to a CMS-HCC V28 payment category. Capture depends on documentation that supports the diagnosis; verify the HCC assignment against the current CMS mapping for the applicable payment year. Coders reviewing E06.5 should check whether additional documentation would support a more specific child code in the same hierarchy that does map to a payment HCC, capturing the correct specificity is the highest-impact RAF improvement available within accurate coding.
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
- •E06.3: Autoimmune thyroiditis: use when Hashimoto's disease with positive autoimmune markers is documented
- •E06.9: Thyroiditis unspecified: avoid when a specific chronic type is identified
- •E06.2: Chronic thyroiditis with transient thyrotoxicosis: use when chronic thyroiditis causes episodic hyperthyroidism