F09
Billable codeUnspecified mental disorder due to known physiological condition
The ICD-10 code for unspecified mental disorder due to known physiological condition is F09.
Clinical notes
Code first
This code represents a manifestation of an underlying disease. Coding convention requires the underlying (etiology) code to be sequenced first, with this code listed second.
- the underlying physiological condition
Excludes1 (not coded here)
An Excludes1 note is a pure exclusion: the excluded condition and this code should never be reported together, because the two conditions cannot occur at the same time (e.g. a congenital form vs. an acquired form of the same disease).
Also known as
Alternate wording, synonyms, or specific conditions that fall under this code, listed to help confirm you've picked the right one.
- Mental disorder NOS due to known physiological condition
- Organic brain syndrome NOS
- Organic mental disorder NOS
- Organic psychosis NOS
- Symptomatic psychosis NOS
Documentation support
General coding-documentation guidance — not a substitute for payer-specific requirements or professional coding judgment.
- •This code describes an unspecified presentation. If the medical record documents a more specific detail (e.g. laterality, type, or affected site), a more specific sibling code should be used instead — see Related codes below.
- •Confirm the excluded condition(s) listed above are not also present — Excludes1 conditions cannot be coded together with this one.
- •This code represents a manifestation. Documentation should identify the underlying condition, which must be coded first.
- •As a general rule, code to the highest level of specificity supported by the documentation in the medical record.
Related codes in this category
- F01Vascular dementianon-billable header
- F02Dementia in other diseases classified elsewherenon-billable header
- F03Unspecified dementianon-billable header
- F04Amnestic disorder due to known physiological condition
- F05Delirium due to known physiological condition
- F06Other mental disorders due to known physiological conditionnon-billable header
- F07Personality and behavioral disorders due to known physiological conditionnon-billable header
- F09Unspecified mental disorder due to known physiological condition
ICD-9-CM equivalent
Informational only — GEM mappings are approximate, not guaranteed one-to-one equivalents. Verify before use in billing.
- 3109Approximate match
Associated MS-DRGs
F09 can serve as the principal diagnosis for these Medicare Severity Diagnosis-Related Groups.
Informational only — actual DRG assignment also depends on procedures, complications/comorbidities (CC/MCC), discharge status, and payer-specific rules not reflected here.