What is ICD-10 code E04.1?

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. It belongs to the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89). E04.1 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. E04.1 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. E04.1 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. E04.1 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for E04.1?

E04.1 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards E04.1 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

What should coders know when reporting E04.1?

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

E04.1: Nontoxic single thyroid nodule — ICD-10

ICD-10-CM Code View

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Code lookupE04.1Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Endocrine, nutritional and metabolic diseases (E00-E89) / Disorders of thyroid gland (E00-E07)

E04.1

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Nontoxic single thyroid nodule

A single lump or nodule in the thyroid gland that is not producing excess thyroid hormone.

Buddy Insight

Nontoxic single thyroid nodule represents a solitary nodule within an otherwise normal thyroid gland with preserved thyroid function (euthyroid state).

CMS-HCC V28

Not risk-adjusted for this model/period.

RAF 0

CMS-HCC V24

Not risk-adjusted for this model/period.

RAF 0

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Not risk-adjusted for this model/period.

RAF 0

RXHCC

Mapped

HCC 44

Thyroid and Parathyroid Disor...

RAF 0.0

Code Trumping

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Code Book Path

Official

E04Other nontoxic goiter

E04.1Nontoxic single thyroid nodule

Inclusion Terms

Official

Colloid nodule (cystic) (thyroid)
Nontoxic uninodular goiter
Thyroid (cystic) nodule NOS

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for E04.1 in this effective period.

Related Child Codes

Official

E04.0Nontoxic diffuse goiter

E04.2Nontoxic multinodular goiter

E04.8Other specified nontoxic goiter

E04.9Nontoxic goiter, unspecified

Includes

Official

ICD-10-CM does not list Includes notes for E04.1 in this effective period.

Excludes 1

Official

congenital goiter (NOS) (diffuse) (parenchymatous) (E03.0)
iodine-deficiency related goiter (E00-E02)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for E04.1 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for E04.1 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for E04.1 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

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.

MEAT Support

HCC Buddy guidance

Documentation should confirm a solitary thyroid nodule with normal thyroid function tests.

Fine-needle aspiration biopsy results (if performed), Bethesda classification, and the surveillance plan should be recorded.

Audit Caution

HCC Buddy guidance

Do not assign this code if the nodule is hyperfunctioning (toxic); use E05.10 instead. Ensure the nodule is truly solitary; multiple nodules require E04.

If fine-needle aspiration reveals malignancy, transition to the appropriate neoplasm code (C73). Do not use this code for thyroid cysts, which may have a different clinical significance. Ensure follow-up surveillance plan is documented per current guidelines.

Common Mistakes

HCC Buddy guidance

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.

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

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

RxHCCHCC 44, Thyroid and Parathyroid Disorders

0.000

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.

Coder workflow notes

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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.