F09 ICD-10-CM

ICD-10-CM code F09 describes unspecified mental disorder due to known physiological condition. Mental symptoms known to stem from a medical condition where the exact syndrome is not specified. It is a billable, specific code valid for claim submission. It is grouped under the “Neurocognitive & Organic Disorders” section of the mental, behavioral, and neurodevelopmental disorders chapter.

When to use F09

Assign a code in this group when a mental or behavioral disturbance is caused by a known physiological condition, such as delirium, dementia, or another organic mental disorder. Base the selection on the documented medical workup and the specific cognitive or behavioral presentation. For F09 specifically, mental symptoms known to stem from a medical condition where the exact syndrome is not specified.

Documentation & billing

Document the underlying etiology, the cognitive or behavioral findings, and whether a behavioral disturbance is present. Pair with an etiology code (for example Alzheimer disease G30.9 or a cerebrovascular code) when the cause is identified.

Common pitfalls

• Coding dementia without documenting whether a behavioral disturbance is present.
• Omitting the underlying etiology code when the cause is known.
• Confusing acute delirium (F05) with chronic dementia.

Common search terms for F09

Clinicians often look up F09 using plain-language terms. This code maps to:

Frequently asked questions