2026 ICD-10-CM Diagnosis Code E05.21Thyrotoxicosis with toxic multinodular goiter with thyrotoxic crisis or storm

ICD-10-CM Codes›E00–E89›E00-E07›E05

ICD-10-CM E05.21
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

E05.21 is a billable ICD-10-CM diagnosis code for thyrotoxicosis with toxic multinodular goiter 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 multinodular goiter. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Thyroid disorders.

Code Identity

ICD-10-CM Code
E05.21
Billable Status
Yes — Valid for Submission
Code Describes
Thyrotoxicosis with toxic multinodular goiter with thyrotoxic crisis or storm
Short Description
Thyrotxcosis w toxic multinodular goiter w thyrotoxic crisis
Parent Code
E05.2
Thyrotoxicosis with toxic multinodular goiter

Code Classification

ChapterE00–E89Endocrine, nutritional and metabolic diseases
SectionE00-E07Disorders of thyroid gland
CategoryE05Thyrotoxicosis [hyperthyroidism]
This CodeE05.21Thyrotoxicosis with toxic multinodular goiter with thyrotoxic crisis or storm

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Multinodular goiter
  • Thyrotoxic crisis
  • Toxic multinodular goiter
  • Toxic multinodular goiter with thyrotoxic crisis
  • Toxic nodular goiter
  • Toxic nodular goiter with thyrotoxic storm

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.

    • Goiter(plunging) (substernal)
      • multinodular (cystic) (nontoxic)
        • toxic or with hyperthyroidism
          • with thyroid storm
    • Goiter(plunging) (substernal)
      • nodular (nontoxic) (due to)
        • with
          • hyperthyroidism
            • with thyroid storm
    • Goiter(plunging) (substernal)
      • nodular (nontoxic) (due to)
        • with
          • thyrotoxicosis
            • with thyroid storm
    • Goiter(plunging) (substernal)
      • nodular (nontoxic) (due to)
        • toxic
          • with thyroid storm
    • Hyperthyroidism(latent) (pre-adult) (recurrent)
      • with
        • goiter (diffuse)
          • nodular (multinodular)
            • with thyroid storm
    • Nodule(s), nodular
      • thyroid (cold) (gland) (nontoxic)
        • with thyrotoxicosis
          • with thyroid storm
    • Nodule(s), nodular
      • thyroid (cold) (gland) (nontoxic)
        • toxic or with hyperthyroidism
          • with thyroid storm
    • Plummer's disease
      • with thyroid storm
    • Struma
      • nodosa (simplex)
        • toxic or with hyperthyroidism
          • with thyroid storm
    • Struma
      • nodosa (simplex)
        • toxic or with hyperthyroidism
          • multinodular
            • with thyroid storm
    • Struma
      • nodosa (simplex)
        • toxicosa
          • with thyroid storm
    • Struma
      • nodosa (simplex)
        • toxicosa
          • multinodular
            • with thyroid storm
    • Thyrotoxicosis(recurrent)
      • with
        • goiter (diffuse)
          • multinodular
            • with thyroid storm
    • Thyrotoxicosis(recurrent)
      • with
        • goiter (diffuse)
          • nodular
            • 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

  • Multinodular Goiter

    nodular goiter characterized by more than one discrete tissue mass.

  • Non-Toxic Multinodular Goiter|Nontoxic multinodular goiter

    a multinodular goiter that is not associated with changes in thyroid function or malignancy.

  • 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.

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 E05.21 to ICD-9-CMHistory

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

ICD-9-CM
242.21 Tox multnod goit w cris
Approximate The match is approximate rather than exact.
ICD-9-CM
242.31 Tox nod goiter w crisis
Approximate The match is approximate rather than exact.

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 E05.21Overview

Is E05.21 (Thyrotoxicosis with toxic multinodular goiter) a billable code?

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

What MS-DRG does E05.21 group to?

When thyrotoxicosis with toxic multinodular goiter 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 E05.21?

Under the General Equivalence Mappings, thyrotoxicosis with toxic multinodular goiter with thyrotoxic crisis or storm converts to ICD-9-CM 242.21 (tox multnod goit w cris) and 242.31 (tox nod goiter w crisis). The mapping is approximate, so confirm the match fits the documentation.

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.