2026 ICD-10-CM Diagnosis Code E03.3Postinfectious hypothyroidism

ICD-10-CM Codes›E00–E89›E00-E07›E03

ICD-10-CM E03.3
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

E03.3 is a billable ICD-10-CM diagnosis code for postinfectious hypothyroidism. 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 post-infectious hypothyroidism. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Thyroid disorders.

Code Identity

ICD-10-CM Code
E03.3
Billable Status
Yes — Valid for Submission
Code Describes
Postinfectious hypothyroidism
Short Description
Postinfectious hypothyroidism
Same as the full description in the CMS dataset.
Parent Code
E03
Other hypothyroidism

Code Classification

ChapterE00–E89Endocrine, nutritional and metabolic diseases
SectionE00-E07Disorders of thyroid gland
CategoryE03Other hypothyroidism
This CodeE03.3Postinfectious hypothyroidism

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Post-infectious hypothyroidism

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.

    • Hypothyroidism(acquired)
      • postinfectious

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

  • Congenital Hypothyroidism

    a condition in infancy or early childhood due to an in-utero deficiency of thyroid hormones that can be caused by genetic or environmental factors, such as thyroid dysgenesis or hypothyroidism in infants of mothers treated with thiouracil during pregnancy. endemic cretinism is the result of iodine deficiency. clinical symptoms include severe mental retardation, impaired skeletal development, short stature, and myxedema.

  • Hypothyroidism

    a syndrome that results from abnormally low secretion of thyroid hormones from the thyroid gland, leading to a decrease in basal metabolic rate. in its most severe form, there is accumulation of mucopolysaccharides in the skin and edema, known as myxedema. it may be primary or secondary due to other pituitary disease, or hypothalamic dysfunction.

Patient EducationClinical

Hypothyroidism

Hypothyroidism, or underactive thyroid, happens when your thyroid gland doesn't make enough thyroid hormones to meet your body's needs.

The full article covers:

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

Read the full article at MedlinePlus

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

Convert E03.3 to ICD-9-CMHistory

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

ICD-9-CM
244.8 Acquired hypothyroid NEC
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 E03.3Overview

Is E03.3 (Other hypothyroidism) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report postinfectious hypothyroidism on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does E03.3 group to?

When postinfectious hypothyroidism 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 E03.3?

Under the General Equivalence Mappings, postinfectious hypothyroidism converts to ICD-9-CM 244.8 (acquired hypothyroid NEC). 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.