Alphabetic Index FY2027

G73.3

Myasthenic syndromes in other diseases classified elsewhere

FY2027Chapter 6: Diseases of the nervous system/G70–G73 Diseases of myoneural junction and muscle

BillableComplete code, valid to report
Care settingsIRF 60% RuleHospice: not accepted as primaryHospital CCIPF Primary · MS-DRG 056–057

G73.3 (also written G733) is a billable ICD-10-CM diagnosis code for myasthenic syndromes in other diseases classified elsewhere. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 3 codes in category G73 (Disorders of myoneural junction and muscle in diseases classified elsewhere). The Alphabetic Index lists it under 8 entries. Its coding notes include a Code first instruction and 8 Excludes2 entries.

Code first

If the underlying condition listed here is present and known, sequence it first.

This code
  • underlying disease, such as:
    • neoplasm (C00-D49)
    • thyrotoxicosis (E05.-)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Also from chapter/block level (8 notes)
Inherited from Chapter 6 Diseases of the nervous system
  • 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)

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

IRF 60% Rule

On the CMS list of diagnoses used to determine presumptive compliance with the IRF 60 percent rule.

Source: CMS IRF Presumptive Compliance-3, FY 2027 IRF PPS final rule files, effective for discharges on or after October 1, 2026

Hospice: not accepted as primary

Not accepted as the principal diagnosis on a hospice claim (bill types 081x and 082x). The Integrated OCE returns an edit for this code.
Reason: Manifestation code. Report the underlying condition first (see the Code first note).

Source: CMS Integrated Outpatient Code Editor (IOCE) v27.3, effective October 1, 2026, edit 86

Hospital CC

Counts as a complication or comorbidity (CC) when reported as a secondary diagnosis on an inpatient claim. It does not count when the principal diagnosis is one of the 72 codes in its exclusion list. Some MS-DRGs also ignore a CC or MCC that defines the DRG.

Source: CMS MS-DRG Definitions Manual v44, effective October 1, 2026, Appendix C

IPF Primary

IPF MS-DRG adjustment. A principal diagnosis of this code groups to one of these MS-DRGs. Which one depends on other facts of the stay, so the factor is a range:

MS-DRGDescriptionFactor
056Degenerative nervous system disorders w MCC1.12
057Degenerative nervous system disorders w/o MCC1.11
A principal diagnosis that groups to none of the 19 designated MS-DRGs gets no MS-DRG adjustment. Otherwise the claim still receives the federal per diem base rate and the other adjustments.

Source: CMS IPF PPS FY 2027 final rule (CMS-1847-F), Addendum A; code lists from the CMS MS-DRG Definitions Manual v44; effective for discharges on or after October 1, 2026

Alphabetic Index terms

Terms the official Alphabetic Index lists for this code. 8 entries