E05.10
BillableThyrotoxicosis with toxic single thyroid nodule 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 E05.10 an HCC code?
No. E05.10 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 E05.10
For E05.10to 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 E05.10 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
E05.10 is the ICD-10-CM diagnosis code for thyrotoxicosis with toxic single thyroid nodule without thyrotoxic crisis or storm. Overactive thyroid caused by a single nodule producing excess thyroid hormone, without a thyroid storm (life-threatening condition). E05.10 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).
E05.10 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 any HCC under V24 or V28, providing no community risk adjustment impact. It maps to RxHCC 44 (Osteoporosis, Vertebral and Pathological Fractures). Accurate coding supports clinical management of this distinct form of hyperthyroidism and prescription drug plan risk adjustment.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E05.10 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
Clinical Significance
Thyrotoxicosis with toxic single thyroid nodule without thyrotoxic crisis, also known as Plummer disease or toxic adenoma, occurs when a single autonomously functioning thyroid nodule produces excess thyroid hormone independent of thyroid-stimulating hormone regulation. Unlike Graves disease, this condition lacks autoimmune features such as ophthalmopathy and typically presents in older patients. The autonomous nodule suppresses the remainder of the thyroid gland.
Documentation Requirements
- ✓Documentation should confirm a single hyperfunctioning thyroid nodule with thyrotoxicosis.
- ✓Thyroid function tests (suppressed thyroid-stimulating hormone, elevated free thyroxine), radioactive iodine uptake scan showing focal uptake in the nodule with suppression of surrounding tissue, and clinical symptoms should be documented.
- ✓Treatment plan (radioactive iodine, surgery, or antithyroid medications) and response should be recorded.
Commonly Confused Codes
- •E04.1 (Nontoxic single thyroid nodule) captures a nodule without hyperthyroidism.
- •E05.11 (Thyrotoxicosis with toxic single thyroid nodule WITH crisis) captures the crisis form.
- •E05.00 (Thyrotoxicosis with diffuse goiter) captures Graves disease, which has a different mechanism.
- •E05.20 (Thyrotoxicosis with toxic multinodular goiter) captures multiple hyperfunctioning nodules.