2026 ICD-10-CM Diagnosis Code F09Unspecified mental disorder due to known physiological condition
ICD-10-CM Codes›F01–F99›F01-F09›F09
- Billable — Valid for Submission
- Not Chronic
F09 is a billable ICD-10-CM diagnosis code for unspecified mental disorder due to known physiological condition. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 974 through 976. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Miscellaneous mental and behavioral disorders/conditions.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Behavior disorder as sequela of cerebral infarction
- Chronic brain syndrome
- Chronic non-psychotic brain syndrome
- Chronic organic mental disorder
- Cognitive changes due to organic disorder
- Cognitive disorder
- Cognitive disorder in remission
- Encephalopathy with AIDS
- Neurocognitive disorder
- Neuropsychiatric disorder due to systemic lupus erythematosus
- Organic brain syndrome co-occurrent with human immunodeficiency virus infection
- Organic brain syndrome with AIDS
- Organic mental disorder
- Organic mental disorder caused by ethanol
- Organic mental disorder caused by hypnotic agent
- Organic mental disorder caused by sedative
- Specific nonpsychotic mental disorders following organic brain damage
- Transient organic mental disorder
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Mental disorder NOS due to known physiological condition
- Organic brain syndrome NOS
- Organic mental disorder NOS
- Organic psychosis NOS
- Symptomatic psychosis NOS
Code First
- the underlying physiological condition
Type 1 Excludes
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
- cognitive - F09
- Disease, diseased - See Also: Syndrome;
- Disorder (of) - See Also: Disease;
- cognitive - F09
- mental (or behavioral) (nonpsychotic) - F99
- general medical condition - F09
- organic or symptomatic - F09
- Organic - See Also: condition;
- brain syndrome - F09
- mental disorder - F09
- psychosis - F09
- organic - F09
- symptomatic - F09
- Syndrome - See Also: Disease;
- brain (nonpsychotic) - F09
- organic - F09
- post-traumatic (nonpsychotic) - F07.81
- psychotic - F09
- psycho-organic - F09
- organic
- brain - F09
External Cause of Injuries IndexGuidance
References for this code in the External Cause of Injuries Index.
- Deficiency, deficient
- cognitive
- Disease, diseased
- mental
- organic
- Disorder(of)
- cognitive
- Disorder(of)
- cognitive
- due to (secondary to) general medical condition
- Disorder(of)
- mental (or behavioral) (nonpsychotic)
- due to (secondary to)
- brain disease, damage and dysfunction
- Disorder(of)
- mental (or behavioral) (nonpsychotic)
- due to (secondary to)
- general medical condition
- Disorder(of)
- mental (or behavioral) (nonpsychotic)
- organic or symptomatic
- Organic
- brain syndrome
- Organic
- mental disorder
- Organic
- psychosis
- Psychosis, psychotic
- organic
- Psychosis, psychotic
- symptomatic
- Syndrome
- brain (nonpsychotic)
- Syndrome
- brain (nonpsychotic)
- with psychosis, psychotic reaction
- Syndrome
- brain (nonpsychotic)
- organic
- Syndrome
- brain (nonpsychotic)
- organic
- post-traumatic (nonpsychotic)
- psychotic
- Syndrome
- brain (nonpsychotic)
- psycho-organic
- Syndrome
- organic
- brain
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Organic Mental Disorder
any decrease in mental functioning in which the cause is not attributable to psychiatric illness, which includes damage from physical trauma, anoxic injury, damage from chemicals or toxins, infection, cancer, and degenerative diseases, including alzheimer's disease, huntington's disease, parkinson's disease, and creutzfeldt-jakob disease.Transient Organic Mental Disorder
an organic mental disorder that is temporary in nature.Cognitive Disorder
a category of psychiatric disorders which are characterized by a deficit in cognition or memory.
Patient EducationClinical
Mental Disorders
Mental disorders (or mental illnesses) are conditions that affect your thinking, feeling, mood, and behavior. They may happen over a short period of time or come and go. Some can be chronic (long-lasting). They can affect your ability to relate to others and function each day..
The full article covers:
- What are mental disorders?
- What are some types of mental disorders?
- What causes mental disorders?
- Who is at risk for mental disorders?
- How are mental disorders diagnosed?
- What are the treatments for mental disorders?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert F09 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About F09Overview
Is F09 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report unspecified mental disorder due to known physiological condition on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does F09 group to?
When unspecified mental disorder due to known physiological condition is the principal diagnosis on an inpatient stay, it groups to MS-DRG 974, 975, 976, with relative weights from 0.8945 to 2.8860 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of F09?
Under the General Equivalence Mappings, unspecified mental disorder due to known physiological condition converts to ICD-9-CM 310.9 (nonpsychot brain syn NOS). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
