ICD-10 Code E05.91 – Thyrotoxicosis, unspecified with thyrotoxic crisis or storm (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E05.91 – Thyrotoxicosis, unspecified with thyrotoxic crisis or storm
What it is
This code identifies thyrotoxicosis when the cause is not specified and the patient is in thyrotoxic crisis, also called thyroid storm. It reflects an acute, severe complication of excess thyroid hormone.
Clinical signs
Clinical features vary; refer to documentation. Typical notes describe marked hyperthyroid symptoms with acute decompensation, such as agitation, confusion, fever, rapid heartbeat, or heart failure.
When to use this code
Use E05.91 when the record states thyrotoxicosis and documents crisis or storm, but does not identify a specific cause such as Graves disease or toxic nodular goiter. You should also use it when the clinician clearly documents thyroid storm with unspecified thyrotoxicosis.
If the chart names a definite etiology, code that more specific diagnosis instead. Check documentation when the term “thyroid storm” appears without enough detail to confirm unspecified thyrotoxicosis.
Do not use for
Do not use this code for uncomplicated thyrotoxicosis without crisis or storm. Do not use it when a more specific hyperthyroidism code is documented.
Coding tip
Look for explicit wording such as “thyroid storm,” “thyrotoxic crisis,” or “thyrotoxicosis with crisis” before assigning E05.91.