ICD-10-CM 2027
ICD-10 code for hypothyroidism
Confirmed by the official ICD-10-CM index entry “arthritis, arthritic (acute) (chronic) (nonpyogenic) (subacute) › in (due to) › hypothyroidism nec”. Page updated September 29, 2026.
About coding hypothyroidism
The ICD-10-CM code for hypothyroidism is E03.9 (Hypothyroidism, unspecified). The official index lists 7 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on E03.9.
It is also searched as underactive thyroid.
Within E03, choose E03.9 (Hypothyroidism, unspecified) only when documentation doesn't support a more specific option: congenital hypothyroidism with diffuse goiter (E03.0), congenital hypothyroidism without goiter (E03.1), hypothyroidism due to medicaments and other exogenous substances (E03.2), postinfectious hypothyroidism (E03.3), atrophy of thyroid (acquired) (E03.4), myxedema coma (E03.5) and other specified hypothyroidism (E03.8).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 643 (Endocrine Disorders with MCC, relative weight 1.6139), DRG 644 (Endocrine Disorders with CC, relative weight 1.0044) and DRG 645 (Endocrine Disorders without CC/MCC, relative weight 0.7459), in MDC 10 (Endocrine, Nutritional and Metabolic Diseases and Disorders), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Related Hypothyroidism codes
Common questions about hypothyroidism ICD-10 codes
What is the ICD-10 code for hypothyroidism?
- E03.9 — Hypothyroidism, unspecified. More specific codes apply when the documentation supports them: E03.0, E03.1, E03.2, E03.3 and others below.
What is the ICD-10 code for congenital hypothyroidism with diffuse goiter?
- E03.0 — Congenital hypothyroidism with diffuse goiter.
What is the ICD-10 code for congenital hypothyroidism without goiter?
- E03.1 — Congenital hypothyroidism without goiter.
What is the ICD-10 code for hypothyroidism due to medicaments and other exogenous substances?
- E03.2 — Hypothyroidism due to medicaments and other exogenous substances.
What is the ICD-10 code for postinfectious hypothyroidism?
- E03.3 — Postinfectious hypothyroidism.
What is the ICD-10 code for atrophy of thyroid (acquired)?
- E03.4 — Atrophy of thyroid (acquired).
What is the ICD-10 code for myxedema coma?
- E03.5 — Myxedema coma.
Is E03.9 billable?
- Yes. E03.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can E03.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict E03.9 as a principal diagnosis.
Is E03.9 a CC or MCC?
- No. E03.9 is neither a CC nor an MCC under MS-DRG v44.0.