2027 ICD-10-CM Diagnosis Code G90.3Multi-system degeneration of the autonomic nervous system
ICD-10-CM Codes›G00–G99›G89-G99›G90
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 199
- Chronic Condition
G90.3 is a billable ICD-10-CM diagnosis code for multi-system degeneration of the autonomic nervous system. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 56 through 57. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 23 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (often hereditary or degenerative).
For Medicare Advantage risk adjustment, G90.3 maps to CMS-HCC Category 199 (Parkinson and Other Degenerative Disease of Basal Ganglia) under the V28 model, adding a risk factor of about 0.615 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
G90.3 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Amyotrophic lateral sclerosis plus syndrome
- Amyotrophic lateral sclerosis with multiple system atrophy
- Ataxia due to multiple system atrophy, cerebellar variant
- Chronic hypotension
- Chronic orthostatic hypotension
- Dementia due to multiple system atrophy
- Multiple system atrophy
- Multiple system atrophy, cerebellar variant
- Multiple system atrophy, Parkinson's variant
- Multisystem degeneration of autonomic nervous system
- Orthostatic hypotension
- Orthostatic hypotension co-occurrent and due to Parkinson's disease
- Parkinsonian syndrome with idiopathic orthostatic hypotension
- Parkinson's disease
- Pure autonomic failure
- Sympathotonic orthostatic hypotension
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to G90.3: its own notes plus those printed at G90 and Chapter 6. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Neurogenic orthostatic hypotension [Shy-Drager]
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- orthostatic hypotension NOS (I95.1)
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name G90.3, its category, or a range that includes it.
Excludes1 4
These codes carry an Excludes1 note naming G90.3: they are not reported together with it, unless the two conditions are unrelated.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Shy-Drager syndrome G90.3
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Shy-Drager Syndrome
a progressive neurodegenerative condition of the central and autonomic nervous systems characterized by atrophy of the preganglionic lateral horn neurons of the thoracic spinal cord. this disease is generally considered a clinical variant of multiple system atrophy. affected individuals present in the fifth or sixth decade with orthostasis and bladder dysfunction; and later develop fecal incontinence; anhidrosis; ataxia; impotence; and alterations of tone suggestive of basal ganglia dysfunction. (from adams et al., principles of neurology, 6th ed, p536)
Patient EducationClinical
Autonomic Nervous System Disorders
Your autonomic nervous system is the part of your nervous system that controls involuntary actions, such as the beating of your heart and the widening or narrowing of your blood vessels. When something goes wrong in this system, it can cause serious problems, including:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert G90.3 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About G90.3Overview
What is the ICD-10 code for multi-system degeneration of the autonomic nervous system?
The ICD-10-CM code for multi-system degeneration of the autonomic nervous system is G90.3 (sometimes written as G903). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is G90.3 (Disorders of autonomic nervous system) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report multi-system degeneration of the autonomic nervous system on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does G90.3 group to?
When multi-system degeneration of the autonomic nervous system is the principal diagnosis on an inpatient stay, it groups to MS-DRG 57, 56, with relative weights from 1.2835 to 2.2649 depending on complications. Higher weights mean higher Medicare reimbursement.
Is G90.3 a CC or MCC?
CMS lists G90.3 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 23 closely related codes in its exclusion list.
Can G90.3 be reported with I95.1?
Not as a rule. The Excludes1 note on G90.3 lists "orthostatic hypotension NOS (I95.1)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is G90.3?
G90.3 (multi-system degeneration of the autonomic nervous system) maps to CMS-HCC Category 199 (Parkinson and Other Degenerative Disease of Basal Ganglia), commonly written as HCC 199, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 78 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 161.
Does G90.3 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, G90.3 adds a risk adjustment factor of about 0.615 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.219 to 0.634 depending on the payment segment). HCC 199 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 199 category page.
