ICD-10 Code E05.31 – Thyrotoxicosis from ectopic thyroid tissue with thyrotoxic crisis or storm (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E05.31 – Thyrotoxicosis from ectopic thyroid tissue with thyrotoxic crisis or storm
What it is
This code identifies severe thyrotoxicosis caused by functioning thyroid tissue located outside the normal thyroid gland, with crisis or storm. It reflects an urgent endocrine emergency requiring precise documentation of the source and severity.
Clinical signs
Clinical features vary; refer to documentation. Typical thyrotoxic storm findings may include marked agitation, confusion, fever, tachycardia, and gastrointestinal upset, with evidence that the thyroid hormone excess comes from ectopic tissue.
When to use this code
Use this code when the record clearly documents thyrotoxicosis from ectopic thyroid tissue and also states thyroid storm or crisis. Apply it when the clinician identifies the ectopic source, such as a lingual or mediastinal thyroid remnant, as the cause.
If the chart only says thyrotoxicosis, ectopic thyroid tissue, or storm separately, check documentation before assigning this code. The combination must be explicit or clearly supported in the note.
Do not use for
Do not use this code for thyrotoxicosis without crisis or storm, or for hyperthyroidism from the normal thyroid gland. Do not assign it when ectopic thyroid tissue is mentioned but no toxic state is documented.
Coding tip
Verify both elements in the note: ectopic thyroid tissue and thyrotoxic crisis or storm.