2027 ICD-10-CM Diagnosis Code G93.7Reye's syndrome

ICD-10-CM Codes›G00–G99›G89-G99›G93

ICD-10-CM G93.7
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

G93.7 is a billable ICD-10-CM diagnosis code for Reye's syndrome. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 91 through 93. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 1 closely related codes. The code is restricted by the Medicare Code Editor to pediatric patients (age 0 through 17). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (neither hereditary nor degenerative).

For Medicare Advantage risk adjustment, G93.7 maps to CMS-HCC Category 127 (Dementia, Mild or Unspecified) under the V28 model, adding a risk factor of about 0.341 for a community, non-dual, aged beneficiary in payment year 2027.

Code Identity

ICD-10-CM Code
G93.7
Billable Status
Yes — Valid for Submission
Code Describes
Reye's syndrome
Short Description
Reye's syndrome
Same as the full description in the CMS dataset.
Parent Code
G93
Other disorders of brain

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG89-G99Other disorders of the nervous system
CategoryG93Other disorders of brain
This CodeG93.7Reye's syndrome

Code EditsBilling

Medicare Code Editor checks that affect claim validity for G93.7.

Pediatric diagnoses
The Medicare Code Editor detects inconsistencies in pediatric cases by checking a patient's age and any diagnosis on the patient's record. The pediatric code edits apply to patients age range is 0–17 years inclusive (e.g., Reye's syndrome, routine child health exam).

Medicare Risk Adjustment (HCC)Billing

G93.7 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.

CMS-HCC V28 Category (Payment Model)
HCC 127— Dementia, Mild or Unspecified
Payment HCC · PY 2027 one of 65 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+0.341
community, non-dual, aged · ranges 0.000–0.438 across segments
Hierarchy
Superseded by HCC 125 and HCC 126
a more severe related category takes the payment when both are reported
Prior Model (CMS-HCC V24)
HCC 52
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
ESRD (V21): HCC 52 · ESRD (V24): HCC 52
ESRD V21 weights: 0.045 dialysis, 0.000–0.328 functioning graft · ESRD V24 weights: 0.042 dialysis, 0.000–0.399 functioning graft
Part D (RxHCC)
RxHCC 112 — Dementia, Except Alzheimer's Disease
also risk-adjusts in the Part D prescription drug model (V08)

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.

  • Reye's syndrome

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to G93.7: its own notes plus those printed at Chapter 6. A note printed at a category, block or chapter applies to every code under it.

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.

From Chapter 6 (G00-G99) Diseases of the nervous system applies to 700 codes
  • 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)

Code First

The underlying condition named in the note is sequenced before this code.

  • poisoning due to salicylates, if applicable (T39.0-, with sixth character 1-4)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

  • code for adverse effect due to salicylates, if applicable (T39.0-, with sixth character 5)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name G93.7, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming G93.7: they are not reported together with it, unless the two conditions are unrelated.

  • E88.4 Mitochondrial metabolism disorders
    Reye's syndrome (G93.7)
  • G71.3 Mitochondrial myopathy, not elsewhere classified
    Reye's syndrome (G93.7)

Excludes2 2

These codes carry an Excludes2 note naming G93.7: its condition is not part of those codes, and both may be reported when the patient has both.

  • G31 Other degenerative diseases of nervous system, not elsewhere classified
    Reye's syndrome (G93.7)
  • Block K70-K77 Diseases of liver
    Reye's syndrome (G93.7)

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NVS020
Other nervous system disorders (neither hereditary nor degenerative)
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Reye Syndrome

    a form of encephalopathy with fatty infiltration of the liver, characterized by brain edema and vomiting that may rapidly progress to seizures; coma; and death. it is caused by a generalized loss of mitochondrial function leading to disturbances in fatty acid and carnitine metabolism.

Patient EducationClinical

Reye Syndrome

Reye syndrome is a rare illness that can affect the blood, liver, and brain of someone who has recently had a viral infection. It always follows another illness. Although it mostly affects children and teens, anyone can get it. It can develop quickly and without warning. It is most common during flu season. Symptoms include:

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert G93.7 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
331.81 Reye's syndrome
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About G93.7Overview

What is the ICD-10 code for Reye's syndrome?

The ICD-10-CM code for Reye's syndrome is G93.7 (sometimes written as G937). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is G93.7 (Other disorders of brain) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report Reye's syndrome on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does G93.7 group to?

When Reye's syndrome is the principal diagnosis on an inpatient stay, it groups to MS-DRG 91, 92, 93, with relative weights from 0.7783 to 1.7050 depending on complications. Higher weights mean higher Medicare reimbursement.

Is G93.7 a CC or MCC?

CMS lists G93.7 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 1 closely related codes in its exclusion list.

Who can G93.7 be reported for?

The Medicare Code Editor checks Reye's syndrome against patient demographics: this code is intended for pediatric patients (age 0 through 17). Claims outside these limits are flagged as inconsistent.

What HCC is G93.7?

G93.7 (Reye's syndrome) maps to CMS-HCC Category 127 (Dementia, Mild or Unspecified), commonly written as HCC 127, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 52 under the retired V24 model. It also maps in the ESRD (V21) and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 112.

Does G93.7 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, G93.7 adds a risk adjustment factor of about 0.341 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.000 to 0.438 depending on the payment segment). A more severe related category (HCC 125 and HCC 126) supersedes it when both are reported. See the full factor table on the HCC 127 category page.