What is ICD-10 code E05.81?

E05.81 is the ICD-10-CM diagnosis code for Other thyrotoxicosis with thyrotoxic crisis or storm. Overactive thyroid from other specified causes, with thyroid storm (severe, life-threatening condition). It belongs to the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89). E05.81 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. E05.81 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. E05.81 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. E05.81 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 E05.81 map to under V28?

E05.81 has no payable CMS-HCC V28 mapping in the final FY2026 CMS file.

What RAF reference is published for E05.81?

E05.81 has no V28 reference coefficient because the final FY2026 source verifies no payable V28 mapping.

What is the V28 vs V24 difference for E05.81?

E05.81 has verified no payable V28 mapping in the final FY2026 source. Select a historical effective period before making any V24 comparison.

What documentation supports E05.81?

Use this code only when the cause of thyrotoxicosis doesn't fit other E05 categories Document the specific cause in the medical record for clarity and future reference E05.81 is not a CMS-HCC V28 payment code in the verified current source, so MEAT is not the payment hook. Documentation still has to support the diagnosis if you report it.

2026 ICD-10-CM E05.81: Other thyrotoxicosis with thyrotoxic

E05.81 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · HCC Buddy coding tools

ICD-10-CM Code View

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Code lookupE05.81

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

E05.81

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

Other thyrotoxicosis with thyrotoxic crisis or storm

Overactive thyroid from other specified causes, with thyroid storm (severe, life-threatening condition).

Buddy Insight

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

N/A

—

Not risk-adjusted for this model/period.

Not mapped

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

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 Disorders

Code-level coefficient reference

Code Book Path

Official

E05Thyrotoxicosis [hyperthyroidism]E05.8Other thyrotoxicosis E05.81Other thyrotoxicosis with thyrotoxic crisis or storm

Inclusion Terms

Official

Overproduction of thyroid-stimulating hormoneInherited from E05.8

Excludes 2

Official

No Excludes 2 notes are included in this display for E05.81. Check the code and parent instructions in the Code Book.

Related Codes

Official

E05.80Other thyrotoxicosis without thyrotoxic crisis or storm

Includes

Official

No Includes notes are included in this display for E05.81. 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, E05
chronic thyroiditis with transient thyrotoxicosis (E06.2)Inherited from E00-E89, E05
neonatal thyrotoxicosis (P72.1)Inherited from E00-E89, E05

Code First

Official

No Code First sequencing instructions are included in this display for E05.81. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for E05.81. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for E05.81. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Document the specific underlying cause of thyrotoxicosis, clinical criteria confirming thyrotoxic crisis (hyperpyrexia, cardiovascular instability, neurological changes), and the critical care interventions administered.

Include the precipitating factor for storm if identifiable, and record the specific rare etiology driving the condition.

MEAT Support

HCC Buddy guidance

Include the precipitating factor for storm if identifiable, and record the specific rare etiology driving the condition.

Audit Caution

HCC Buddy guidance

The 'other' category requires that the provider has identified a specific etiology that does not fall into the preceding E05 subcategories.

If the etiology is unknown, use E05.91 instead.

The crisis component must be explicitly documented as thyroid storm or thyrotoxic crisis.

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 E05.81 an HCC code?

E05.81 is not in the CMS-HCC V28 or V24 community payment model. E05.81 has a separate mapping under the Part D RxHCC model (HCC 44 (Thyroid Disorders)); the applicable result needs member context.

Code: E05.81
Description: Other thyrotoxicosis with thyrotoxic crisis or storm
HCC (V28): No CMS-HCC V28 mapping
RAF reference coefficient: —
Billable: Yes
Payment year: 2026

HCC Category Mapping

RxHCCHCC 44, Thyroid Disorders

Not separately weighted

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 E05.81 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for E05.81

For E05.81, 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

E05.81 is the ICD-10-CM diagnosis code for other thyrotoxicosis with thyrotoxic crisis or storm. Overactive thyroid from other specified causes, with thyroid storm (severe, life-threatening condition). E05.81 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).

E05.81 has no mapping under the CMS-HCC V28 or V24 community payment models. E05.81 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.

Use this code only when the cause of thyrotoxicosis doesn't fit other E05 categories.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for E05.81 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Use this code only when the cause of thyrotoxicosis doesn't fit other E05 categories
•Document the specific cause in the medical record for clarity and future reference

Clinical Significance

Other thyrotoxicosis with thyrotoxic crisis represents thyroid storm arising from uncommon etiologies such as TSH-secreting pituitary adenomas, gestational thyrotoxicosis, or drug-induced hyperthyroidism that has progressed to systemic decompensation. The rare etiology combined with storm physiology creates significant diagnostic and management complexity. Mortality is high without prompt recognition and aggressive multi-modal treatment.

Documentation Requirements

✓Document the specific underlying cause of thyrotoxicosis, clinical criteria confirming thyrotoxic crisis (hyperpyrexia, cardiovascular instability, neurological changes), and the critical care interventions administered.
✓Include the precipitating factor for storm if identifiable, and record the specific rare etiology driving the condition.

Child Codes

E05.80Other thyrotoxicosis without thyrotoxic crisis or storm

E05.81Other thyrotoxicosis with thyrotoxic crisis or storm

Code Hierarchy

└E05Thyrotoxicosis [hyperthyroidism]└E05.8Other thyrotoxicosis └E05.81Other thyrotoxicosis with thyrotoxic crisis or storm

└E05.81Other thyrotoxicosis with thyrotoxic crisis or storm

E05.81 ICD-10-CM Code: Other thyrotoxicosis with thyrotoxic crisis or storm

HCC Buddy Code Card

E05.81

Is E05.81 an HCC code?

HCC Category Mapping

MEAT review for E05.81

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What This Code Means

Coding Tips

Clinical Significance

Documentation Requirements

Child Codes

Code Hierarchy

Work E05.81 in HCC Buddy