E04.1
BillableNontoxic single thyroid nodule
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is E04.1 an HCC code?
No. E04.1 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 E04.1
For E04.1to 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 E04.1 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
E04.1 is the ICD-10-CM diagnosis code for nontoxic single thyroid nodule. A single lump or nodule in the thyroid gland that is not producing excess thyroid hormone. E04.1 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).
E04.1 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.
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). The primary coding importance is clinical documentation for malignancy surveillance and surgical decision-making rather than risk adjustment.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E04.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Distinguish between nontoxic nodule (E04.1) and toxic nodule (E05.1); thyroid function tests should confirm nontoxic status
- •Document nodule size and any imaging findings; note if fine needle aspiration or biopsy was performed
Clinical Significance
Nontoxic single thyroid nodule represents a solitary nodule within an otherwise normal thyroid gland with preserved thyroid function (euthyroid state). Thyroid nodules are extremely common, found in up to 50% of adults on ultrasound, but the clinical significance lies primarily in excluding malignancy. Approximately 5-15% of thyroid nodules are malignant, making appropriate evaluation with ultrasound characteristics assessment and potential fine-needle aspiration biopsy essential.
Documentation Requirements
- ✓Documentation should confirm a solitary thyroid nodule with normal thyroid function tests.
- ✓Thyroid ultrasound findings including nodule size, echogenicity, margins, calcifications, and vascularity pattern should be documented per American College of Radiology Thyroid Imaging Reporting and Data System criteria.
- ✓Fine-needle aspiration biopsy results (if performed), Bethesda classification, and the surveillance plan should be recorded.
Commonly Confused Codes
- •E04.2 (Nontoxic multinodular goiter) is used when multiple nodules are present.
- •E05.10 (Thyrotoxicosis with toxic single thyroid nodule) captures a hyperfunctioning nodule with thyrotoxicosis.
- •D44.0 (Neoplasm of uncertain behavior of thyroid gland) may be considered for suspicious nodules.
- •C73 (Malignant neoplasm of thyroid gland) is used when malignancy is confirmed.