What is ICD-10 code E01.0?

E01.0 is the ICD-10-CM diagnosis code for Iodine-deficiency related diffuse (endemic) goiter. An enlarged thyroid gland (goiter) that develops in areas with low iodine in the diet, affecting the entire thyroid uniformly rather than forming nodules. E01.0 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. E01.0 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. E01.0 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. E01.0 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 E01.0?

E01.0 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 E01.0 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 E01.0?

Document the geographic region or endemic area when possible, as this helps establish the iodine-deficiency etiology Distinguish from multinodular goiter (E01.1) by confirming the goiter is diffuse rather than nodular

E01.0: Iodine-deficiency related diffuse (endemic)

ICD-10-CM Code View

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Code lookupE01.0Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

E01.0

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

Iodine-deficiency related diffuse (endemic) goiter

An enlarged thyroid gland (goiter) that develops in areas with low iodine in the diet, affecting the entire thyroid uniformly rather than forming nodules.

Buddy Insight

Iodine-deficiency related diffuse (endemic) goiter represents thyroid enlargement due to chronic iodine deficiency in geographic regions where iodine intake is insufficient.

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

E01Iodine-deficiency related thyroid disorders and allied conditions

E01.0Iodine-deficiency related diffuse (endemic) goiter

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for E01.0 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for E01.0 in this effective period.

Related Child Codes

Official

E01.1Iodine-deficiency related multinodular (endemic) goiter

E01.2Iodine-deficiency related (endemic) goiter, unspecified

E01.8Other iodine-deficiency related thyroid disorders and allied conditions

Includes

Official

ICD-10-CM does not list Includes notes for E01.0 in this effective period.

Excludes 1

Official

congenital iodine-deficiency syndrome (E00.-)
subclinical iodine-deficiency hypothyroidism (E02)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for E01.0 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for E01.0 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for E01.0 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation should confirm diffuse thyroid enlargement attributed to iodine deficiency, with distinction from other causes of goiter (autoimmune thyroiditis, Graves disease).

Thyroid function tests, iodine status assessment if available, thyroid ultrasound findings showing diffuse enlargement without dominant nodules, and any symptoms related to goiter size (dysphagia, dyspnea) should be recorded.

The endemic or iodine-deficiency etiology must be specified.

MEAT Support

HCC Buddy guidance

Documentation should confirm diffuse thyroid enlargement attributed to iodine deficiency, with distinction from other causes of goiter (autoimmune thyroiditis, Graves disease).

The endemic or iodine-deficiency etiology must be specified.

Audit Caution

HCC Buddy guidance

Distinguish iodine-deficiency related goiter from other causes of diffuse thyroid enlargement.

In developed nations with iodine supplementation, endemic goiter is uncommon, and other etiologies should be considered first.

Do not assign this code for multinodular goiter (use E01.1).

Ensure thyroid function status is documented as it affects management.

Common Mistakes

HCC Buddy guidance

E04.0 (Nontoxic diffuse goiter) is the appropriate code when the goiter is not related to iodine deficiency.

E01.1 (Iodine-deficiency related multinodular goiter) is used when the goiter has progressed to multinodular morphology.

E05.00 (Thyrotoxicosis with diffuse goiter) captures a toxic goiter with hyperthyroidism.

E06.3 (Autoimmune thyroiditis) may also cause diffuse goiter but has a different etiology.

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 E01.0 an HCC code?

No. E01.0 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 E01.0

For E01.0to 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 E01.0 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

E01.0 is the ICD-10-CM diagnosis code for iodine-deficiency related diffuse (endemic) goiter. An enlarged thyroid gland (goiter) that develops in areas with low iodine in the diet, affecting the entire thyroid uniformly rather than forming nodules. E01.0 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).

E01.0 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 clinical importance lies in documenting the etiology of thyroid disease for appropriate long-term management rather than risk adjustment.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E01.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Document the geographic region or endemic area when possible, as this helps establish the iodine-deficiency etiology
•Distinguish from multinodular goiter (E01.1) by confirming the goiter is diffuse rather than nodular

Clinical Significance

Iodine-deficiency related diffuse (endemic) goiter represents thyroid enlargement due to chronic iodine deficiency in geographic regions where iodine intake is insufficient. The thyroid gland enlarges diffusely as a compensatory response to produce adequate thyroid hormone despite limited iodine availability. While patients often maintain euthyroid status initially, progression to hypothyroidism or development of autonomous nodules with thyrotoxicosis can occur over time.

Documentation Requirements

✓Documentation should confirm diffuse thyroid enlargement attributed to iodine deficiency, with distinction from other causes of goiter (autoimmune thyroiditis, Graves disease).
✓Thyroid function tests, iodine status assessment if available, thyroid ultrasound findings showing diffuse enlargement without dominant nodules, and any symptoms related to goiter size (dysphagia, dyspnea) should be recorded.
✓The endemic or iodine-deficiency etiology must be specified.

Commonly Confused Codes

•E04.0 (Nontoxic diffuse goiter) is the appropriate code when the goiter is not related to iodine deficiency.
•E01.1 (Iodine-deficiency related multinodular goiter) is used when the goiter has progressed to multinodular morphology.
•E05.00 (Thyrotoxicosis with diffuse goiter) captures a toxic goiter with hyperthyroidism.
•E06.3 (Autoimmune thyroiditis) may also cause diffuse goiter but has a different etiology.