ICD-10 Code E03.4 – Atrophy of thyroid (acquired) (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E03.4 – Atrophy of thyroid (acquired)
What it is
E03.4 identifies acquired shrinkage or loss of thyroid tissue, usually resulting in reduced thyroid function. Use it when the record documents atrophic thyroid disease rather than another specific cause of hypothyroidism.
Clinical signs
Clinical features vary; refer to documentation. Findings may include signs of hypothyroidism, and the thyroid gland may be small or difficult to palpate on exam.
When to use this code
Use this code when the provider documents atrophy of the thyroid as the diagnosis. It is also appropriate when acquired thyroid atrophy is the stated cause of hypothyroidism and no more specific etiology is recorded.
Code the documented condition as written and avoid assuming autoimmune or post-treatment causes unless clearly stated. Check documentation if the note only says “hypothyroidism” without identifying atrophy.
Do not use for
Do not use E03.4 for congenital hypothyroidism, thyroiditis, or hypothyroidism due to surgery, radiation, or medication unless atrophy is specifically documented. Check documentation.
Coding tip
Assign E03.4 only when “atrophy” or “atrophic thyroid” appears in the provider’s diagnosis, assessment, or problem list.