Sick-euthyroid syndrome

This code represents non-thyroidal illness syndrome (NTIS), also known as sick euthyroid syndrome, a condition characterized by abnormal thyroid hormone levels in the absence of primary thyroid disease. It typically occurs in patients with severe acute or chronic non-thyroidal illnesses, where the body's metabolic response to stress alters thyroid hormone metabolism.

Use this code when documentation clearly indicates a diagnosis of sick euthyroid syndrome, often seen in critically ill patients, those with severe infections, trauma, or chronic systemic diseases. Supporting documentation should reflect normal TSH levels with altered peripheral thyroid hormone concentrations (e.g., low T3, normal or low T4) and the absence of primary thyroid pathology.

• Do not code this as a primary thyroid disorder; it is a manifestation of an underlying severe illness.
• Always code the underlying severe non-thyroidal illness first, as this condition is secondary to it.
• Ensure documentation differentiates this from hypothyroidism or hyperthyroidism, which are primary thyroid gland dysfunctions.