What is ICD-10 code E03.1?

E03.1 is the ICD-10-CM diagnosis code for Congenital hypothyroidism without goiter. A condition present at birth where the thyroid doesn't produce enough hormones, but the thyroid gland is normal in size without goiter. It belongs to the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89). E03.1 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. E03.1 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. E03.1 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. E03.1 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.

Which HCC does E03.1 map to under V28?

E03.1 does not map to a CMS-HCC V28 payment category. Check the current CMS-HCC V28 model file for payment year 2026 rather than an older V24 tip sheet.

What does E03.1 pay in RAF?

E03.1 has no separately stated V28 community RAF weight. If it is not a V28 payment HCC, it adds nothing to a community RAF score.

What is the V28 vs V24 difference for E03.1?

E03.1 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 community model rewards E03.1 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's V28/V24 community RAF score in either version. It does, however, map under the Part D RxHCC model (Thyroid and Parathyroid Disorders), which affects the ESRD and/or Part D (RxHCC) risk scores. Coders should check whether provider documentation supports a more specific child code that does map to a community payment HCC.

What documentation supports E03.1?

Confirm absence of goiter to differentiate from E03.0; document thyroid size as normal on examination Newborn screening results (elevated TSH, low T4) should be documented to support diagnosis E03.1 is not a CMS-HCC payment code, so MEAT is not the payment hook. Documentation still has to support the diagnosis if you report it.

2026 ICD-10-CM E03.1: Congenital hypothyroidism without

E03.1 is not a CMS-HCC payment code. MEAT criteria · RAF calculator · free HCC coding tools

ICD-10-CM Code View

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Code lookupE03.1Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

E03.1

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

Congenital hypothyroidism without goiter

A condition present at birth where the thyroid doesn't produce enough hormones, but the thyroid gland is normal in size without goiter.

Buddy Insight

Congenital hypothyroidism without goiter encompasses thyroid agenesis (absent thyroid gland), thyroid ectopia (thyroid tissue in an abnormal location such as sublingual), and thyroid hypoplasia.

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

N/A

—

Not risk-adjusted for this model/period.

Not mapped

ACA/HHS

N/A

—

Not risk-adjusted for this model/period.

Not mapped

ESRD/PACE

N/A

—

Not risk-adjusted for this model/period.

Not mapped

RXHCC

Mapped

HCC 44

Thyroid and Parathyroid Disor...

RAF 0.070

Code Book Path

Official

E03Other hypothyroidism

E03.1Congenital hypothyroidism without goiter

Inclusion Terms

Official

Aplasia of thyroid (with myxedema)
Congenital atrophy of thyroid
Congenital hypothyroidism NOS

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for E03.1 in this effective period.

Related Child Codes

Official

E03.0Congenital hypothyroidism with diffuse goiter

E03.2Hypothyroidism due to medicaments and other exogenous substances

E03.3Postinfectious hypothyroidism

E03.4Atrophy of thyroid (acquired)

E03.5Myxedema coma

Includes

Official

ICD-10-CM does not list Includes notes for E03.1 in this effective period.

Excludes 1

Official

iodine-deficiency related hypothyroidism (E00-E02)
postprocedural hypothyroidism (E89.0)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for E03.1 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for E03.1 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for E03.1 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation should confirm congenital hypothyroidism without goiter, with newborn screening results, confirmatory thyroid function tests, and thyroid imaging (ultrasound or nuclear thyroid scan) to determine the underlying cause (agenesis, ectopia, hypoplasia).

Current levothyroxine replacement dose, adherence, thyroid function monitoring results, and developmental status should be documented at follow-up visits.

MEAT Support

HCC Buddy guidance

Current levothyroxine replacement dose, adherence, thyroid function monitoring results, and developmental status should be documented at follow-up visits.

Audit Caution

HCC Buddy guidance

This code requires the absence of goiter

if thyroid enlargement is present, use E03.0 instead. Ensure the diagnosis is congenital, not acquired hypothyroidism developing later in childhood or adulthood. Transient neonatal hypothyroidism should not be coded with this permanent congenital diagnosis. Document the specific cause (agenesis, ectopia, hypoplasia) when known to support the diagnosis.

Common Mistakes

HCC Buddy guidance

E03.0 (Congenital hypothyroidism with diffuse goiter) is used when a goiter is present, suggesting dyshormonogenesis.

E00.0-E00.9 (Congenital iodine-deficiency syndrome) requires an iodine-deficiency etiology.

E03.9 (Hypothyroidism, unspecified) lacks the congenital specificity.

P72.2 (Other neonatal goiter, not elsewhere classified) captures neonatal thyroid conditions not classified as congenital hypothyroidism.

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is E03.1 an HCC code?

E03.1 is not in the CMS-HCC V28 or V24 community payment model, but it does map to Thyroid and Parathyroid Disorders under the Part D RxHCC model.

Code: E03.1
Description: Congenital hypothyroidism without goiter
HCC (V28): No CMS-HCC V28 mapping
RAF: —
Billable: Yes
Payment year: 2026

HCC Category Mapping

RxHCCHCC 44, Thyroid and Parathyroid Disorders

0.070

Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. 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.

Work E03.1 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for E03.1

For E03.1 to 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 E03.1 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

E03.1 is the ICD-10-CM diagnosis code for congenital hypothyroidism without goiter. A condition present at birth where the thyroid doesn't produce enough hormones, but the thyroid gland is normal in size without goiter. E03.1 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).

E03.1 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 a CMS-HCC V28 payment category. Capture depends on documentation that supports the diagnosis; verify the HCC assignment against the current CMS mapping for the applicable payment year. Coders reviewing E03.1 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-impact RAF improvement available within accurate coding.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E03.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Confirm absence of goiter to differentiate from E03.0; document thyroid size as normal on examination
•Newborn screening results (elevated TSH, low T4) should be documented to support diagnosis

Clinical Significance

Congenital hypothyroidism without goiter encompasses thyroid agenesis (absent thyroid gland), thyroid ectopia (thyroid tissue in an abnormal location such as sublingual), and thyroid hypoplasia. It is the most common form of congenital hypothyroidism, detected through universal newborn screening programs. Without prompt levothyroxine replacement, affected infants develop cretinism with severe intellectual disability, growth failure, and neurological impairment.

Documentation Requirements

✓Documentation should confirm congenital hypothyroidism without goiter, with newborn screening results, confirmatory thyroid function tests, and thyroid imaging (ultrasound or nuclear thyroid scan) to determine the underlying cause (agenesis, ectopia, hypoplasia).
✓Current levothyroxine replacement dose, adherence, thyroid function monitoring results, and developmental status should be documented at follow-up visits.

Commonly Confused Codes

•E03.0 (Congenital hypothyroidism with diffuse goiter) is used when a goiter is present, suggesting dyshormonogenesis.
•E00.0-E00.9 (Congenital iodine-deficiency syndrome) requires an iodine-deficiency etiology.
•E03.9 (Hypothyroidism, unspecified) lacks the congenital specificity.
•P72.2 (Other neonatal goiter, not elsewhere classified) captures neonatal thyroid conditions not classified as congenital hypothyroidism.