F05

F05 is an ICD-10-CM diagnostic code used in medical classification to designate delirium due to a known physiological condition. It is part of the broader range F00-F09, which covers organic mental disorders and related conditions. The code is used in medical records and billing to indicate that a patient’s delirium is linked to an underlying physiologic problem rather than a primary psychiatric disorder or substance-related illness.

Delirium itself is characterized by an acute, fluctuating disturbance of attention and cognition, with disturbance of consciousness and perception. It typically develops over hours to days and tends to fluctuate in severity throughout the day. Common underlying causes for delirium coded as F05 include infections, metabolic or electrolyte disturbances, organ failure, hypoxia, medication effects, or withdrawal from substances.

Diagnosis relies on clinical assessment, often supported by brief cognitive tests and observation, with investigations aimed at identifying reversible physiologic contributing factors. Management focuses on treating the underlying condition, ensuring patient safety, reorientation, adequate hydration and nutrition, and minimizing exposure to deliriogenic medications. Nonpharmacologic approaches are preferred; antipsychotics or sedatives may be considered in specific circumstances but carry risk.

Prognosis varies with the underlying illness and its reversibility; delirium often resolves with treatment of the medical condition but can be associated with longer hospital stays or increased mortality in older or frail patients. Notes: ICD-10-CM coding practices may differ by country or edition.