ICD-10-CM Code For Unspecified Mental Disorder Due To Known Physiological Condition: Group Overview

The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code group F09 includes mental disorders that arise as a direct physiological consequence of a known medical condition where specific psychiatric diagnoses are not further specified, encompassing disturbances of cognition, mood, perception, or behavior linked to the underlying condition. These ICD-10-CM diagnosis codes are used to document clinical scenarios where mental symptoms are attributed to another medical, neurological, or systemic illness, capturing the relationship between the physiological cause and the psychiatric presentation. Accurate coding within the ICD-10-CM F09 group supports proper claim adjudication, complete clinical documentation, and appropriate reimbursement.

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ICD-10-CM F09: Unspecified Mental Disorder Due To Known Physiological Condition Overview

This code group represents mental disorders that are attributable to an identified physiological condition but are not specified further in documentation. It targets neuropsychiatric manifestations secondary to medical, neurological, or systemic conditions and affects mental status, mood, behavior, or cognition. Accurate coding matters for correct claim processing and to reflect the medical complexity that influences reimbursement and care planning.

When to Use

Use a code from this group when clinical documentation links mental symptoms to a known physiological condition but does not provide a more specific psychiatric diagnosis. These codes apply when the provider documents that the mental disorder is secondary to an identified medical cause and no additional specification is available in the record.

ICD-10-CM Codes

1 rows

ICD-10-CM Code	Description
F09	Unspecified mental disorder due to known physiological condition

DRG Codes

4 rows

DRG Code	Description
884	Organic Disturbances and Intellectual Disability
974	HIV with Major Related Condition with MCC
975	HIV with Major Related Condition with CC
976	HIV with Major Related Condition without CC/MCC

Typical Clinical Scenarios

An elderly patient with known advanced Parkinson disease is brought to clinic by family for progressive memory loss, fluctuating attention, and new visual hallucinations over several months. Neurocognitive testing and review of medications do not fully explain the changes, and clinicians determine the neuropsychiatric symptoms are attributable to the underlying neurological condition rather than a primary psychiatric disorder; a diagnosis from this group is assigned to capture the unspecified mental disorder due to the known physiological condition. Typical codes: F09
A middle-aged patient hospitalized after a moderate traumatic brain injury develops acute confusional state, disorientation, and agitation during the inpatient stay; metabolic and infectious causes have been excluded and symptoms are judged to be related to the structural brain injury. Because the mental status disturbance is due to a documented physiological brain condition but the specific psychiatric manifestation is not coded more precisely, a code from this group is used. Typical codes: F09
An adult with long-standing hepatic cirrhosis presents to the emergency department with worsening sleep–wake cycle reversal, lethargy, and intermittent agitation; laboratory testing supports hepatic encephalopathy as the precipitant of the behavioral and cognitive changes, yet the mental disorder is not classified to a more specific psychiatric category. In this setting, clinicians record a diagnosis from this group to indicate an unspecified mental disorder secondary to the known medical condition. Typical codes: F09

Related Codes

F01-VASCULAR-DEMENTIA

ICD-10-CM Code For Vascular Dementia: Group Overview

F02-DEMENTIA-IN-OTHER-DISEASES

ICD-10-CM Code For Dementia In Other Diseases Classified Elsewhere: Group Overview

F03-UNSPECIFIED-DEMENTIA

ICD-10-CM Code For Unspecified Dementia: Group Overview

F04-AMNESTIC-DISORDER-DUE-TO-KNOWN-PHYSIOLOGICAL-CONDITION

ICD-10-CM Code For Amnestic Disorder Due To Known Physiological Condition: Group Overview

F05-DELIRIUM-DUE-TO-PHYSIOLOGICAL-CONDITION

ICD-10-CM Code For Delirium Due To Known Physiological Condition: Group Overview

F06-OTHER-MENTAL-DISORDERS-SECONDARY

ICD-10-CM Code For Other Mental Disorders Due To Known Physiological Condition: Group Overview

F07-PERSONALITY-AND-BEHAVIORAL-DISORDERS

ICD-10-CM Code For Personality And Behavioral Disorders Due To Known Physiological Condition: Group Overview

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

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When to Use

ICD-10-CM Codes

1 rows

ICD-10-CM Code	Description
F09	Unspecified mental disorder due to known physiological condition

DRG Codes

4 rows

DRG Code	Description
884	Organic Disturbances and Intellectual Disability
974	HIV with Major Related Condition with MCC
975	HIV with Major Related Condition with CC
976	HIV with Major Related Condition without CC/MCC

Typical Clinical Scenarios

An elderly patient with known advanced Parkinson disease is brought to clinic by family for progressive memory loss, fluctuating attention, and new visual hallucinations over several months. Neurocognitive testing and review of medications do not fully explain the changes, and clinicians determine the neuropsychiatric symptoms are attributable to the underlying neurological condition rather than a primary psychiatric disorder; a diagnosis from this group is assigned to capture the unspecified mental disorder due to the known physiological condition. Typical codes: F09
A middle-aged patient hospitalized after a moderate traumatic brain injury develops acute confusional state, disorientation, and agitation during the inpatient stay; metabolic and infectious causes have been excluded and symptoms are judged to be related to the structural brain injury. Because the mental status disturbance is due to a documented physiological brain condition but the specific psychiatric manifestation is not coded more precisely, a code from this group is used. Typical codes: F09
An adult with long-standing hepatic cirrhosis presents to the emergency department with worsening sleep–wake cycle reversal, lethargy, and intermittent agitation; laboratory testing supports hepatic encephalopathy as the precipitant of the behavioral and cognitive changes, yet the mental disorder is not classified to a more specific psychiatric category. In this setting, clinicians record a diagnosis from this group to indicate an unspecified mental disorder secondary to the known medical condition. Typical codes: F09

Related Codes

F01-VASCULAR-DEMENTIA

ICD-10-CM Code For Vascular Dementia: Group Overview

F02-DEMENTIA-IN-OTHER-DISEASES

ICD-10-CM Code For Dementia In Other Diseases Classified Elsewhere: Group Overview

F03-UNSPECIFIED-DEMENTIA

ICD-10-CM Code For Unspecified Dementia: Group Overview

F04-AMNESTIC-DISORDER-DUE-TO-KNOWN-PHYSIOLOGICAL-CONDITION

ICD-10-CM Code For Amnestic Disorder Due To Known Physiological Condition: Group Overview

F05-DELIRIUM-DUE-TO-PHYSIOLOGICAL-CONDITION

ICD-10-CM Code For Delirium Due To Known Physiological Condition: Group Overview

F06-OTHER-MENTAL-DISORDERS-SECONDARY

ICD-10-CM Code For Other Mental Disorders Due To Known Physiological Condition: Group Overview

F07-PERSONALITY-AND-BEHAVIORAL-DISORDERS

ICD-10-CM Code For Personality And Behavioral Disorders Due To Known Physiological Condition: Group Overview

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

ICD-10-CM Code For Unspecified Mental Disorder Due To Known Physiological Condition: Group Overview

Sign up for ICD-10-CM Code For Unspecified Mental Disorder Due To Known Physiological Condition: Group Overview policy alerts

ICD-10-CM F09: Unspecified Mental Disorder Due To Known Physiological Condition Overview

ICD-10-CM Code For Unspecified Mental Disorder Due To Known Physiological Condition: Group Overview

Sign up for ICD-10-CM Code For Unspecified Mental Disorder Due To Known Physiological Condition: Group Overview policy alerts

ICD-10-CM F09: Unspecified Mental Disorder Due To Known Physiological Condition Overview

When to Use

ICD-10-CM Codes

DRG Codes

Typical Clinical Scenarios

Related Codes

When should a coder use `F09`?

How does coding `F09` affect claims and documentation?

What clinical presentations are encompassed by `F09`?

Which DRGs are related to the `F09` code group?

Does `F09` indicate the physiological cause itself?

References

When to Use

ICD-10-CM Codes

DRG Codes

Typical Clinical Scenarios

Related Codes

When should a coder use `F09`?

How does coding `F09` affect claims and documentation?

What clinical presentations are encompassed by `F09`?

Which DRGs are related to the `F09` code group?

Does `F09` indicate the physiological cause itself?

References