E03.9 Hypothyroidism, unspecified

The ICD-10-CM code for Hypothyroidism, unspecified is E03.9 (FY2026). It is a billable, claim-ready diagnosis code.

Choosing between codes? See the guide: ICD-10 code for hypothyroidism.

Classification

Chapter

4: Endocrine, nutritional and metabolic diseases (E00-E89)

Section

E00-E07: Disorders of thyroid gland (E00-E07)

Category E03

9 codes (8 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to E03.9:

• Myxedema (adult) (idiocy) (infantile) (juvenile)
• Hoffmann's syndrome
• Hypothyroidism (acquired)
• Cataract (cortical) (immature) (incipient) › myxedema
• Insufficiency, insufficient › thyroid (gland) (acquired)
• Anemia (essential) (general) (hemoglobin deficiency) (infantile) (primary) (profound) › due to (in) (with) › myxedema
• Arthritis, arthritic (acute) (chronic) (nonpyogenic) (subacute) › in (due to) › hypothyroidism NEC
• Arthropathy › in (due to) › hypothyroidism

Inclusion Terms

• Myxedema NOS

U.S. Hospital Utilization

• An estimated 3,613,140 U.S. inpatient stays in 2023 included E03.9 among the documented diagnoses.
• 4,765 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Prevalence & Statistics

• Nearly 5 out of 100 Americans ages 12 years and older have hypothyroidism, although most cases are mild or have few obvious symptoms. (NIDDK (National Institute of Diabetes and Digestive and Kidney Diseases) - Hypothyroidism (Underactive Thyroid), 2021)

Official Coding Guidelines

Diabetes mellitus (TOC entry)

a. Diabetes mellitus ................................................................................................................... 39

Obesity (TOC entry)

b. Obesity .................................................................................................................................. 42

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)
• NIDDK (National Institute of Diabetes and Digestive and Kidney Diseases) - Hypothyroidism (Underactive Thyroid) (2021)