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G90.3

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🧬 ICD-10 CM G90.3 — Multi-system Degeneration of the Autonomic Nervous System

Billable Code Confirmed

ICD-10 CM G90.3 is a valid, billable 4-character diagnosis code for FY2026. The 1st through 3rd characters (G90) define the category of autonomic nervous system disorders, and the 4th character (3) specifies multi-system degeneration. No additional characters are required.

Non-Billable Parent Codes — Never Submit These

  • ❌ G90 — 3-character header — Lacks specification of the specific autonomic disorder.

Always submit G90.3 when neurogenic orthostatic hypotension, Shy-Drager syndrome, or Multiple System Atrophy is documented.

Clinical Context: Neurogenic vs. Non-Neurogenic

ICD-10-CM G90.3 captures orthostatic hypotension only when it is confirmed as neurogenic or driven by autonomic failure. Standard, non-neurogenic orthostatic hypotension (e.g., from dehydration) maps to I95.1.

Code Classification

ICD-10-CM Diagnosis Code — wRVU, assistant payable, and global period fields are not applicable. Direct reader to commonly associated CPT codes below for profee procedural associations (such as autonomic testing).

🔍 Code Description

ICD-10 CM G90.3 classifies multi-system degeneration of the autonomic nervous system. This code represents a group of progressive, neurodegenerative disorders characterized by the failure of the autonomic nervous system, which controls involuntary body functions like blood pressure, heart rate, and digestion.

The most common conditions captured by this code are Multiple System Atrophy (MSA) and Shy-Drager syndrome. Clinically, a hallmark of these conditions is severe Neurogenic Orthostatic Hypotension (NOH) — a sudden, dangerous drop in blood pressure upon standing without the normal compensatory increase in heart rate, due to sympathetic nervous system failure.

🌳 Code Tree / Hierarchy

G00-G99 Diseases of the nervous system ❌ Non-billable
│
├── G89 Pain, not elsewhere classified ❌ Non-billable
├── G90 Disorders of autonomic nervous system ❌ Non-billable
│ │
│ ├── G90.0 Idiopathic peripheral autonomic neuropathy ❌ Non-billable
│ ├── G90.1 Familial dysautonomia [Riley-Day] ✅ Billable
│ ├── G90.2 Horner's syndrome ✅ Billable
│ ├── G90.3 Multi-system degeneration of the autonomic nervous system ◀ THIS CODE ✅ Billable
│ ├── G90.4 Autonomic dysreflexia ✅ Billable
│ └── G90.A Postural orthostatic tachycardia syndrome [POTS] ✅ Billable
│
└── G91 Hydrocephalus ❌ Non-billable

MSA / Parkinson's Plus Insight

Do not default to a Parkinson’s disease code (G20.-) if the provider documents “Multiple System Atrophy” or “Parkinson’s Plus Syndrome.” These conditions are clinically distinct from classic Parkinson’s disease due to their severe primary autonomic failure and map strictly to G90.3.

✅ Includes

The following clinical terms and scenarios map to G90.3 when documented:

  • Neurogenic orthostatic hypotension [NOH]

  • Shy-Drager syndrome

  • Multiple system atrophy (MSA), including the Parkinsonian variant

  • Parkinsonism with orthostatic hypotension

❌ Excludes

Excludes 1 — Cannot Be Coded Simultaneously with G90.3

CodeDescriptionNote
I95.1Orthostatic hypotension NOSI95.1 represents non-neurogenic postural hypotension. It is mutually exclusive to the neurogenic form classified in G90.3.
G20.-Parkinson’s diseaseParkinson’s disease is excluded; if the patient has classic PD, code G20.-. If they have Parkinsonism as part of Multiple System Atrophy, use G90.3.
G31.2Degeneration of nervous system due to alcoholMutually exclusive underlying etiology.

Excludes 1 Violation Risk

A common denial trigger is billing both G90.3 and I95.1 on the same claim. If the documentation supports Neurogenic Orthostatic Hypotension, only G90.3 is reported.

Excludes 2 — May Be Coded in Addition if Separately Present

CodeDescriptionNote
I95.2Orthostatic hypotension due to drugsCan be coded alongside if the patient has baseline MSA/neurogenic failure and an acute drug-induced exacerbation, though careful sequencing is required.

📋 Clinical Overview

Phenotype Distinction: Orthostatic Hypotension Types

Accurate code selection requires differentiating the underlying cause of the blood pressure drop.

FeatureG90.3 — Neurogenic Orthostatic HypotensionI95.1 — Orthostatic Hypotension NOS
Underlying CauseAutonomic / Sympathetic nervous system failureDehydration, blood loss, prolonged bed rest
Heart Rate ResponseBlunted: BP drops with no compensatory HR increaseNormal/Tachycardic: BP drops with HR increase ≥15 bpm
Clinical ValidationTilt-table testing, abnormal QSART, α-synuclein biopsyStandard orthostatic vital signs
Associated SyndromesMultiple System Atrophy, Shy-Drager, Parkinson’s PlusHypovolemia, vasovagal responses

CDI Query Trigger — Neurogenic Clarification

If a patient with known autonomic neuropathy, dysautonomia, or a neurodegenerative disease is admitted with “orthostatic hypotension,” query the provider: “Is the orthostatic hypotension neurogenic in nature (such as part of multi-system degeneration), or non-neurogenic?” Capturing G90.3 properly signals the neurological complexity.

Manifestations & Symptom Burden

  • Cardiovascular: Severe dizziness, pre-syncope, or syncope upon standing.

  • Genitourinary: Neurogenic bladder, urinary retention, or incontinence.

  • Gastrointestinal: Gastroparesis, severe constipation.

  • Motor: ataxia, rigid muscles, tremors (if Parkinsonian variant is present).

Coding Manifestations

Always code the documented manifestations. Examples include:

  • R55 — Syncope and collapse

  • K31.84 — Gastroparesis

  • N31.9 — Neuromuscular dysfunction of bladder, unspecified

💰 HCC Risk Adjustment (CMS-HCC v28)

FieldDetail
CMS-HCC Model Versionv28 (2024-2025 Implementation)
HCC Assignment✅ Mapped
HCC CategoryHCC 199 — Parkinson’s and Huntington’s Diseases
RAF Coefficient~0.615 (varies by demographic/status)

G90.3 maps directly to the Parkinson’s disease risk category and contributes significantly to the RAF score under v28.

Capture Annually

As a chronic, irreversible neurodegenerative condition, G90.3 must be captured annually on a face-to-face encounter. Providers must document active assessment (e.g., “MSA with NOH — adjusting fludrocortisone, continue fall precautions”).

🏥 DRG Assignment

MDC 01 — Diseases and Disorders of the Nervous System

DRGTitleEst. Relative Weight*
DRG 056Degenerative nervous system disorders with MCC~1.45 - 1.65
DRG 057Degenerative nervous system disorders without MCC~0.85 - 1.05

Approximate. Verify against IPPS FY2026 Final Rule tables.

Sequencing and Complications

G90.3 is typically the principal diagnosis when a patient is admitted directly for autonomic failure crisis or severe syncope workup due to MSA. When admitted for trauma (e.g., a fall resulting in a fracture), the injury is sequenced first, and G90.3 functions as a secondary diagnosis that explains the etiology of the fall.

🔗 Related ICD-10-CM Codes

Dysautonomia and POTS Variants

CodeDescription
G90.3Multi-system degeneration of the autonomic nervous system ← This Code
G90.APostural orthostatic tachycardia syndrome [POTS]
G90.09Other idiopathic peripheral autonomic neuropathy

🛠️ Commonly Associated CPT Codes (Neurology / Cardiology)

Outpatient and Profee Setting Context

Diagnosis of neurogenic orthostatic hypotension often requires specialized autonomic function testing in the outpatient setting to confirm the lack of sympathetic reflex compensation.

CPT CodeDescriptionProfee Coding Notes (Modifier 26)
95921Testing of autonomic nervous system function; cardiovagal innervationMeasures heart rate response to deep breathing and Valsalva.
95922Testing of autonomic nervous system function; vasomotor adrenergic innervationTilt table testing for BP response to establish G90.3.
95924Testing of autonomic nervous system function; combined parasympathetic and sympatheticComprehensive autonomic lab testing.
99214Office or other outpatient visit, established patient, mod-high MDMReflects the prescription management of complex vasoactive drugs (e.g., midodrine, droxidopa).

🔬 ICD-10-CM Diagnosis Crosswalk

Since G90.3 is a systemic disease, it frequently requires additional diagnosis codes to fully capture the patient’s presenting symptoms.

Condition AreaDiagnosis FocusClinical Application
TraumaFalls due to SyncopeIf the NOH caused a fall, code the injury (e.g., S01.81XA Laceration of head) and the fall external cause (e.g., W01.0XXA) alongside G90.3.
CardiacSyncopeCode R55 (Syncope and collapse) as an additional code if the patient experienced an acute fainting episode leading to admission.

💊 Coding Scenarios and Examples

Scenario 1 — Outpatient Neurology Clinic: Multiple System Atrophy

Clinical Vignette: A 62-year-old male presents with progressively worsening dizziness upon standing and mild parkinsonian rigidity. Recent autonomic lab testing (tilt-table) revealed a significant blood pressure drop without a compensatory heart rate increase, consistent with sympathetic failure. The provider diagnoses Multiple System Atrophy (parkinsonian type) with neurogenic orthostatic hypotension and starts the patient on droxidopa.

Principal Diagnosis:

  • G90.3 — Multi-system degeneration of the autonomic nervous system (Captures both the MSA and the neurogenic orthostatic hypotension)

Scenario 2 — Inpatient Admission: Fall Secondary to Shy-Drager

Clinical Vignette: A 68-year-old female with known Shy-Drager syndrome is admitted after a syncopal episode in her kitchen resulting in a 4 cm facial laceration. Vitals in the ED show severe orthostatic hypotension (sitting BP 130/80, standing BP 85/50). The laceration is sutured, and she is admitted for IV hydration and adjustment of her midodrine regimen to stabilize her autonomic failure.

Principal Diagnosis:

  • S01.81XA — Laceration without foreign body of other part of head, initial encounter (Reason for admission/treatment)

Secondary Diagnoses:

  • R55 — Syncope and collapse (The acute event)

  • G90.3 — Multi-system degeneration of the autonomic nervous system (Underlying etiology driving the syncope and requiring medication adjustment)

  • W01.0XXA — Fall on same level from slipping, tripping and stumbling, initial encounter

MS-DRG Assignment: Groups to a surgical or medical trauma DRG depending on the laceration repair, with G90.3 providing severity mapping.

Scenario 3 — CDI Query: Clarification of Orthostatic Hypotension

Clinical Vignette: Provider documents: “Patient evaluated for severe orthostatic hypotension and Parkinson’s Plus syndrome. Continues to have profound dizziness when standing. Adjusting fludrocortisone dose.”

Action / Outcome:

The documentation lacks the specific link between the orthostatic hypotension and the neurodegenerative disease. If coded as is, the coder would have to use I95.1 (non-neurogenic) and a less specific Parkinsonism code. A query is required.

Query Response: Provider updates documentation to confirm: “The patient has Multiple System Atrophy causing neurogenic orthostatic hypotension.”

Corrected ICD-10-CM Coding:

  • G90.3 — Multi-system degeneration of the autonomic nervous system (Replaces the need for I95.1 and an unspecified Parkinson’s code)

⚠️ Coding Pitfalls and Tips

Pitfall or Tip
❌Using I95.1 instead of G90.3. Do not use I95.1 for cases where autonomic testing clearly indicates sympathetic failure or the provider specifically documents “neurogenic” orthostatic hypotension.
❌Defaulting to G20. Coding G20.- (Parkinson’s disease) when the provider explicitly diagnoses “Multiple System Atrophy” (MSA) or “Parkinson’s Plus.” MSA is distinctly captured under G90.3.
✅Query for Vague Terminology. If the provider documents “dysautonomia” with severe blood pressure drops, query to see if it meets the criteria for multi-system degeneration (G90.3) versus unspecified autonomic neuropathy (G90.9) to ensure proper HCC capture.
✅Check the Excludes 1 Note. Never report I95.1 on the same claim as G90.3. The system will trigger an Excludes 1 denial edit.

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