E05.30
BillableThyrotoxicosis from ectopic thyroid tissue without thyrotoxic crisis or storm
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is E05.30 an HCC code?
No. E05.30 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 E05.30
For E05.30to 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 E05.30 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
E05.30 is the ICD-10-CM diagnosis code for thyrotoxicosis from ectopic thyroid tissue without thyrotoxic crisis or storm. Overactive thyroid caused by thyroid tissue located outside the normal thyroid gland, without thyroid storm. E05.30 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).
E05.30 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. While this code does not map to CMS-HCC v28 or v24 models, capturing it supports prescription drug risk adjustment for patients requiring thyroid-related medications. Coders reviewing E05.30 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-leverage RAF improvement available within accurate coding.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E05.30 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Ectopic thyroid tissue is thyroid hormone-producing tissue in an abnormal location (e.g., tongue, chest)
- •Confirm absence of crisis; if thyroid storm is present, use E05.31
Clinical Significance
Thyrotoxicosis from ectopic thyroid tissue represents excess thyroid hormone production from hormonally active thyroid tissue in an aberrant anatomic location such as the lingual, sublingual, mediastinal, or ovarian (struma ovarii) regions. This condition requires lifelong monitoring as the ectopic tissue may not respond to conventional antithyroid therapies and surgical excision may be necessary. Without crisis, the condition may present with typical hyperthyroid symptoms including weight loss, tremor, and tachycardia.
Documentation Requirements
- ✓Document the specific anatomic location of the ectopic thyroid tissue when identified (e.g., lingual, substernal, ovarian).
- ✓Record current thyroid function tests (TSH, free T4, free T3) and explicitly state the absence of thyrotoxic crisis or storm.
- ✓Include the treatment approach and whether the condition is managed medically or surgically.
Commonly Confused Codes
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