2026 ICD-10-CM Diagnosis Code E05.91Thyrotoxicosis, unspecified with thyrotoxic crisis or storm

ICD-10-CM Codes›E00–E89›E00-E07›E05

ICD-10-CM E05.91
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

E05.91 is a billable ICD-10-CM diagnosis code for thyrotoxicosis, unspecified with thyrotoxic crisis or storm. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 643 through 645. Coders also document this condition as thyrotoxic crisis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Thyroid disorders.

Code Identity

ICD-10-CM Code
E05.91
Billable Status
Yes — Valid for Submission
Code Describes
Thyrotoxicosis, unspecified with thyrotoxic crisis or storm
Short Description
Thyrotoxicosis, unspecified with thyrotoxic crisis or storm
Same as the full description in the CMS dataset.
Parent Code
E05.9
Thyrotoxicosis, unspecified

Code Classification

ChapterE00–E89Endocrine, nutritional and metabolic diseases
SectionE00-E07Disorders of thyroid gland
CategoryE05Thyrotoxicosis [hyperthyroidism]
This CodeE05.91Thyrotoxicosis, unspecified with thyrotoxic crisis or storm

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Thyrotoxic crisis

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Cardiomyopathy(familial) (idiopathic)
      • metabolic
        • thyrotoxic
          • with thyroid storm
    • Cardiomyopathy(familial) (idiopathic)
      • thyrotoxic
        • with thyroid storm
    • Chloasma(skin) (idiopathic) (symptomatic)
      • eyelid
        • hyperthyroid
          • with thyroid storm
    • Disease, diseased
      • heart (organic)
        • hyperthyroid
          • with thyroid storm
    • Disease, diseased
      • heart (organic)
        • thyrotoxic
          • with thyroid storm
    • Disease, diseased
      • thyroid (gland)
        • heart
          • with thyroid storm
    • Failure, failed
      • Note
        • thyrotoxic
          • with
            • thyroid storm
    • Hyperthyroidism(latent) (pre-adult) (recurrent)
      • with
        • storm
    • Myasthenia
      • syndrome
        • in
          • thyrotoxicosis
            • with thyroid storm
    • Myocardiopathy(congestive) (constrictive) (familial) (hypertrophic nonobstructive) (idiopathic) (infiltrative) (obstructive) (primary) (restrictive) (sporadic)
      • thyrotoxic
        • with storm
    • Myopathy
      • in (due to)
        • thyrotoxicosis (hyperthyroidism)
          • with thyroid storm
    • Myxedema(adult) (idiocy) (infantile) (juvenile)
      • circumscribed
        • with storm
    • Myxedema(adult) (idiocy) (infantile) (juvenile)
      • localized (pretibial)
        • with storm
    • Neuropathy, neuropathic
      • peripheral (nerve)
        • autonomic
          • in (due to)
            • hyperthyroidism
              • with thyroid storm
    • Syndrome
      • myasthenic
        • in
          • thyrotoxicosis (hyperthyroidism)
            • with thyroid storm
    • Thyrotoxic
      • heart disease or failure
        • with thyroid storm
    • Thyrotoxicosis(recurrent)
      • with
        • thyroid storm
    • Thyrotoxicosis(recurrent)
      • heart
        • with thyroid storm

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR END001
Thyroid disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Thyrotoxicosis

    a hypermetabolic syndrome caused by excess thyroid hormones which may come from endogenous or exogenous sources. the endogenous source of hormone may be thyroid hyperplasia; thyroid neoplasms; or hormone-producing extrathyroidal tissue. thyrotoxicosis is characterized by nervousness; tachycardia; fatigue; weight loss; heat intolerance; and excessive sweating.

  • Chronic Thyroiditis with Transient Thyrotoxicosis|Chronic thyroiditis with transient thyrotoxicosis

    persistent and long-standing thyroiditis associated with temporary elevations of thyroid hormones.

  • Neonatal Thyrotoxicosis|Infantile Hyperthyroidism

    a hypermetabolic syndrome characterized by tachycardia, palpitations, tremor, weight loss, and moist skin that is caused by the elevation of thyroid hormone levels in the serum of the newborn infant or thyroid-axis receptor activation, most commonly due to transplacental passage of thyroid stimulating globulins.

  • Other Thyrotoxicosis with Thyrotoxic Crisis or Storm|Other thyrotoxicosis with thyrotoxic crisis or storm

    evidence of other thyrotoxicosis with thyrotoxic crisis or storm not specified elsewhere.

  • Other Thyrotoxicosis without Thyrotoxic Crisis or Storm|Other thyrotoxicosis without thyrotoxic crisis or storm

    evidence of other thyrotoxicosis without thyrotoxic crisis or storm not specified elsewhere.

  • Thyrotoxicosis

    a hypermetabolic syndrome caused by the elevation of thyroid hormone levels in the serum. signs and symptoms include tachycardia, palpitations, tremor, weight loss, warm weather intolerance, and moist skin. causes include graves disease, toxic nodular goiter, toxic thyroid nodule, and lymphocytic thyroiditis.

  • Thyrotoxicosis Factitia with Thyrotoxic Crisis or Storm|Thyrotoxicosis factitia with thyrotoxic crisis or storm

    evidence of thyrotoxicosis factitia with thyrotoxic crisis or storm.

  • Thyrotoxicosis Factitia without Thyrotoxic Crisis or Storm|Thyrotoxicosis factitia without thyrotoxic crisis or storm

    evidence of thyrotoxicosis factitia without thyrotoxic crisis or storm.

  • Thyrotoxicosis from Ectopic Thyroid Tissue with Thyrotoxic Crisis|Thyrotoxicosis from ectopic thyroid tissue with thyrotoxic crisis

    evidence of thyrotoxicosis from ectopic thyroid tissue with thyrotoxic crisis.

  • Thyrotoxicosis from Ectopic Thyroid Tissue without Thyrotoxic Crisis|Thyrotoxicosis from ectopic thyroid tissue without thyrotoxic crisis

    evidence of thyrotoxicosis from ectopic thyroid tissue without thyrotoxic crisis.

  • Thyrotoxicosis with Diffuse Goiter with Thyrotoxic Crisis or Storm|Thyrotoxicosis with diffuse goiter with thyrotoxic crisis or storm

    evidence of thyrotoxicosis with diffuse goiter with thyrotoxic crisis or storm.

  • Thyrotoxicosis with Diffuse Goiter without Thyrotoxic Crisis|Thyrotoxicosis with diffuse goiter without thyrotoxic crisis

    evidence of thyrotoxicosis with diffuse goiter without thyrotoxic crisis.

  • Thyrotoxicosis with Toxic Multinodular Goiter with Thyrotoxic Crisis|Thyrotoxicosis with toxic multinodular goiter with thyrotoxic crisis

    evidence of thyrotoxicosis with toxic multinodular goiter with thyrotoxic crisis.

  • Thyrotoxicosis with Toxic Multinodular Goiter without Thyrotoxic Crisis|Thyrotoxicosis with toxic multinodular goiter without thyrotoxic crisis

    evidence of thyrotoxicosis with toxic multinodular goiter without thyrotoxic crisis.

  • Thyrotoxicosis with Toxic Single Thyroid Nodule with Thyrotoxic Crisis|Thyrotoxicosis with toxic single thyroid nodule with thyrotoxic crisis

    evidence of thyrotoxicosis with toxic single thyroid nodule with thyrotoxic crisis.

  • Thyrotoxicosis with Toxic Single Thyroid Nodule without Thyrotoxic Crisis|Thyrotoxicosis with toxic sing thyroid nodule without thyrotoxic crisis

    evidence of thyrotoxicosis with toxic single thyroid nodule without thyrotoxic crisis.

  • Thyrotoxicosis, Unspecified with Thyrotoxic Crisis or Storm|Thyrotoxicosis, unspecified with thyrotoxic crisis or storm

    evidence of thyrotoxicosis, unspecified with thyrotoxic crisis or storm.

  • Thyrotoxicosis, Unspecified without Thyrotoxic Crisis or Storm|Thyrotoxicosis, unspecified without thyrotoxic crisis or storm

    evidence of thyrotoxicosis, unspecified without thyrotoxic crisis or storm.

Patient EducationClinical

Hyperthyroidism

Hyperthyroidism, or overactive thyroid, happens when your thyroid gland makes more thyroid hormones than your body needs.

The full article covers:

  • What is hyperthyroidism?
  • What causes hyperthyroidism?
  • Who is at risk for hyperthyroidism?
  • What are the symptoms of hyperthyroidism?
  • What other problems can hyperthyroidism cause?
  • How is hyperthyroidism diagnosed?
  • What are the treatments for hyperthyroidism?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert E05.91 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
242.91 Thyrotox NOS w crisis
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About E05.91Overview

Is E05.91 (Thyrotoxicosis, unspecified) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report thyrotoxicosis, unspecified with thyrotoxic crisis or storm on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does E05.91 group to?

When thyrotoxicosis, unspecified with thyrotoxic crisis or storm is the principal diagnosis on an inpatient stay, it groups to MS-DRG 643, 644, 645, with relative weights from 0.7683 to 1.6461 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of E05.91?

Under the General Equivalence Mappings, thyrotoxicosis, unspecified with thyrotoxic crisis or storm converts to ICD-9-CM 242.91 (thyrotox NOS w crisis). The mapping is a direct match.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.