E06.4
BillableDrug-induced thyroiditis
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is E06.4 an HCC code?
No. E06.4 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 E06.4
For E06.4to 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 E06.4 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
E06.4 is the ICD-10-CM diagnosis code for drug-induced thyroiditis. Thyroid inflammation caused by medications or drugs, which may resolve after discontinuation of the offending agent. E06.4 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).
E06.4 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 drug-related costs of managing both the thyroiditis and potential thyroid replacement therapy.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E06.4 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Always document the specific drug or medication causing the thyroiditis in the medical record
- •Common culprits include amiodarone, lithium, interferon, and checkpoint inhibitors
Clinical Significance
Drug-induced thyroiditis is an inflammatory thyroid condition caused by medications, most commonly amiodarone, lithium, interferon-alpha, immune checkpoint inhibitors (nivolumab, pembrolizumab), and tyrosine kinase inhibitors. The condition can manifest as either destructive thyroiditis with transient thyrotoxicosis or as direct inhibition of thyroid hormone synthesis causing hypothyroidism. Recognition is critical because management depends on both the type of thyroiditis and the necessity of continuing the causative medication.
Documentation Requirements
- ✓Document the specific causative medication, the temporal relationship between drug initiation and thyroiditis onset, thyroid function tests, and whether the manifestation is thyrotoxic or hypothyroid.
- ✓Record whether the offending medication can be discontinued or must be continued with thyroid management, and assign an additional adverse effect code for the responsible drug.
Use Additional Code
Commonly Confused Codes
- •
- •
- •