E03.9 ICD-10-CM Code: Hypothyroidism, unspecified
E03.9 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · HCC coding software
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FY 2026 Apr update / Endocrine, nutritional and metabolic diseases (E00-E89) / Disorders of thyroid gland (E00-E07)
E03.9
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceHypothyroidism, unspecified
Hypothyroidism where the specific cause or type has not been determined or documented.
Buddy Insight
Hypothyroidism, unspecified, is the most commonly assigned hypothyroidism code, capturing thyroid underfunction where the specific etiology or type has not been determined or documented.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
MappedHCC 44
Code-level coefficient reference
Code Book Path
Inclusion Terms
Official- Myxedema NOS
Excludes 2
OfficialNo Excludes 2 notes are included in this display for E03.9. Check the code and parent instructions in the Code Book.
Related Codes
Includes
OfficialNo Includes notes are included in this display for E03.9. Check the code and parent instructions in the Code Book.
Excludes 1
Official- transitory endocrine and metabolic disorders specific to newborn (P70-P74)Inherited from E00-E89, E03
- iodine-deficiency related hypothyroidism (E00-E02)Inherited from E00-E89, E03
- postprocedural hypothyroidism (E89.0)Inherited from E00-E89, E03
Code First
OfficialNo Code First sequencing instructions are included in this display for E03.9. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for E03.9. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for E03.9. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 E03.9 an HCC code?
E03.9 is not in the CMS-HCC V28 or V24 community payment model. E03.9 has a separate mapping under the Part D RxHCC model (HCC 44 (Thyroid Disorders)); the applicable result needs member context.
- Code
- E03.9
- Description
- Hypothyroidism, unspecified
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF reference coefficient
- —
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. 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 context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.
Work E03.9 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for E03.9
For E03.9, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.
- 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
Coder workflow notes
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What This Code Means
E03.9 is the ICD-10-CM diagnosis code for hypothyroidism, unspecified. Hypothyroidism where the specific cause or type has not been determined or documented. E03.9 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).
E03.9 has no mapping under the CMS-HCC V28 or V24 community payment models. E03.9 has a separate mapping under the Part D RxHCC model (HCC 44 (Thyroid Disorders)); the applicable result needs member context. Do not assign V28 risk adjustment value from this page; verify the applicable model and payment year before using this code for risk adjustment.
This is a default code; attempt to determine the underlying cause (autoimmune, iodine deficiency, post-surgical) before using this code.
HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for E03.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
Clinical Significance
Hypothyroidism, unspecified, is the most commonly assigned hypothyroidism code, capturing thyroid underfunction where the specific etiology or type has not been determined or documented. Primary hypothyroidism from chronic autoimmune thyroiditis is the most frequent underlying cause in clinical practice. Despite its non-specific nature, this code represents a prevalent chronic condition requiring lifelong monitoring and thyroid hormone replacement therapy.
Documentation Requirements
- ✓Documentation requires a confirmed diagnosis of hypothyroidism with supporting thyroid function tests (elevated thyroid-stimulating hormone, low or low-normal free thyroxine).
- ✓While this unspecified code has minimal documentation requirements, providers should ideally document the etiology (autoimmune, iatrogenic, post-surgical) to enable more specific code assignment.
- ✓Current levothyroxine dose and most recent thyroid-stimulating hormone level should be recorded.
Commonly Confused Codes
- •E03.8 (Other specified hypothyroidism) is used when a specific type is identified.
- •E03.2 (Hypothyroidism due to medicaments) captures drug-induced hypothyroidism.
- •E89.0 (Postprocedural hypothyroidism) captures post-surgical hypothyroidism.
- •E06.3 (Autoimmune thyroiditis) identifies the underlying cause but does not inherently indicate hypothyroidism.
- •E02 (Subclinical iodine-deficiency hypothyroidism) has a specific iodine-deficiency etiology.