Chronic thyroiditis with transient thyrotoxicosis

This diagnosis code signifies an inflammatory condition of the thyroid gland that is chronic in nature, but is temporarily accompanied by symptoms of hyperthyroidism. This transient hyperthyroid state is typically self-limiting and does not represent true Graves' disease or other primary hyperthyroid disorders.

Apply this code when documentation indicates a patient has ongoing thyroid inflammation, such as Hashimoto's thyroiditis, but is experiencing a temporary period of elevated thyroid hormone levels. This often occurs during the destructive phase of thyroiditis before the gland becomes hypothyroid. Documentation should clearly state both the chronic thyroiditis and the transient thyrotoxicosis.

• Do not code with autoimmune thyroiditis (E06.3) as per the Excludes1 note; these conditions are mutually exclusive.
• Ensure the documentation specifies "transient" thyrotoxicosis to differentiate from sustained hyperthyroidism.
• This code is appropriate when the thyrotoxicosis is a direct consequence of the chronic thyroiditis, not an independent condition.