E06.1
BillableSubacute thyroiditis
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is E06.1 an HCC code?
No. E06.1 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 E06.1
For E06.1to 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 E06.1 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
E06.1 is the ICD-10-CM diagnosis code for subacute thyroiditis. Inflammation of the thyroid gland that develops over weeks to months, often following a viral infection, causing temporary thyroid dysfunction. E06.1 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).
E06.1 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 captures the prescription costs for anti-inflammatory and potentially hormonal therapy during the disease course.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E06.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the timeline of symptom onset to distinguish from acute thyroiditis (E06.0) or chronic forms
- •Note any preceding viral illness or upper respiratory infection in the medical record
Clinical Significance
Subacute thyroiditis (de Quervain thyroiditis) is a self-limited inflammatory condition typically following a viral upper respiratory infection, presenting with painful thyroid enlargement, fever, and a characteristic triphasic clinical course of thyrotoxicosis, hypothyroidism, and recovery. The condition is distinguished from other thyroid disorders by markedly elevated ESR and low radioactive iodine uptake during the thyrotoxic phase. Most patients recover full thyroid function within 6-12 months.
Documentation Requirements
- ✓Document the temporal relationship to antecedent viral illness, thyroid tenderness and enlargement on examination, laboratory findings (elevated ESR, thyroid function tests), and the current phase of the triphasic course (thyrotoxic, hypothyroid, or recovery).
- ✓Record treatment with NSAIDs or corticosteroids if applicable.
Excludes 1 — Do NOT code together
- autoimmune thyroiditis (E06.3)
Commonly Confused Codes
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