Anxiety disorder due to known physiological condition

This code signifies an anxiety disorder that is directly caused by an underlying medical condition, rather than being a primary psychiatric disorder. The anxiety symptoms are a physiological consequence of the medical illness, medication side effect, or substance withdrawal (excluding alcohol and psychoactive substances explicitly covered elsewhere). The medical condition is considered the etiological factor for the anxiety.

Apply this code when documentation clearly links anxiety symptoms to a specific, identifiable physiological condition. Examples include anxiety secondary to hyperthyroidism, pheochromocytoma, or certain neurological disorders. The physician's notes should explicitly state the causal relationship between the medical condition and the anxiety.

• Always code the underlying physiological condition first, followed by this code.
• Ensure the documentation explicitly states "due to" or "secondary to" the physiological condition.
• Differentiate from primary anxiety disorders (F40.-, F41.-) and substance-induced anxiety (F10-F19 with .180, .280, .980).