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G73.3 ICD-10-CM Code: Myasthenic syndromes in other diseases classified elsewhere

Compare with another code for G73.3Check this code on a claim

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Official instructions
3 code-first instructions
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 75 · RxHCC V08 category 153

What these terms mean →

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too, and is marked with where it comes from.

Code firstSequence the underlying condition before this code
  • underlying disease, such as:
  • neoplasm (C00-D49)
  • thyrotoxicosis (E05.-)

Where it sits Source: CMS/NCHS

Under:Chapter 6: Diseases of the Nervous SystemG70-G73 Diseases of myoneural junction and muscleG73 Disorders of myoneural junction and muscle in diseases classified elsewhere

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 056 — DEGENERATIVE NERVOUS SYSTEM DISORDERS WITH MCC (MDC 01)
  • MS-DRG 057 — DEGENERATIVE NERVOUS SYSTEM DISORDERS WITHOUT MCC (MDC 01)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 196 — Myasthenia Gravis without (Acute) Exacerbation and Other Myoneural Disorders

Other models: CMS-HCC V22 HCC 75 · RxHCC V08 HCC 153

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for G73.3 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Code First

Underlying conditions that must be sequenced before this code.

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

Coder workflow for G73.3

MedCoder structured workflow — derived from this code’s own official record

Before you code G73.3

  1. G73.3 is a manifestation code (“in diseases classified elsewhere”). Confirm the underlying condition is documented and sequence it first; a manifestation code is not reported as the first-listed or principal diagnosis. The etiology/manifestation convention (Guidelines I.A.13).

    See the official tabular notes · Guide: Manifestation codes and Code First sequencing →

Choose the right path

  1. Is the underlying (etiologic) condition the Code First note names documented?
    Yes → Sequence the underlying condition first, then G73.3.
    No → A manifestation code needs its underlying condition — query before reporting it.

    ReviewE05

Consider G73.3. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
The underlying (etiologic) condition
Named in the Code First note; sequenced before this code when documented (Guidelines I.A.13).

Official instructions as workflow

  • Code First — sequencing check(3 notes)

    Coding workflow: Check whether the underlying or etiologic condition the note names is documented. When it is, sequence it before G73.3. Do not add an underlying condition the record does not document.

    ReviewE05

    See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The underlying condition the Code First note names is documented alongside this condition.

Coding question: How are the two sequenced?

Path: Review the Code First note.

Reason: The underlying condition is sequenced first and the manifestation follows (Guidelines I.A.13).

ReviewE05

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Myasthenic syndromes in other diseases classified elsewhere is a billable ICD-10-CM diagnosis code (G73.3).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • Principal-diagnosis restriction. This is a manifestation code: the Medicare Code Editor requires the underlying condition (etiology) to be sequenced first, with this code reported after it.
  • CC as a secondary diagnosis (FY2027). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name G73.3 or its code family, from the CMS ICD-10-CM tabular instructional notes and the CMS ICD-10-CM Index to Diseases and Injuries. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Code First instruction: M62.84 — Sarcopenia (via G73.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

Referenced by 3 Index etiology/manifestation pairs across 3 chapters: D49.9 — Neoplasm of unspecified behavior of unspecified site, D51.0 — Vitamin B12 deficiency anemia due to intrinsic factor deficiency, E34.9 — Endocrine disorder, unspecified.

The ICD-10-CM Index lists these etiology codes with this code in brackets — the manifestation, reported second.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 72 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 056 (MDC 01), DRG 057 (MDC 01).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):NVS018 — Myopathies.

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

E13.43 — Other specified diabetes mellitus with diabetic autonomic (poly)neuropathy, E13.44 — Other specified diabetes mellitus with diabetic amyotrophy, E13.49 — Other specified diabetes mellitus with other diabetic neurological complication, E13.618 — Other specified diabetes mellitus with other diabetic arthropathy, E13.620 — Other specified diabetes mellitus with diabetic dermatitis, E13.621 — Other specified diabetes mellitus with foot ulcer, E13.622 — Other specified diabetes mellitus with other skin ulcer, E13.628 — Other specified diabetes mellitus with other skin complications, E13.630 — Other specified diabetes mellitus with periodontal disease, E13.638 — Other specified diabetes mellitus with other oral complications, E13.649 — Other specified diabetes mellitus with hypoglycemia without coma, E13.65 — Other specified diabetes mellitus with hyperglycemia, E13.69 — Other specified diabetes mellitus with other specified complication, E13.8 — Other specified diabetes mellitus with unspecified complications, G70.00 — Myasthenia gravis without (acute) exacerbation, G70.01 — Myasthenia gravis with (acute) exacerbation, G70.80 — Lambert-Eaton syndrome, unspecified, G96.9 — Disorder of central nervous system, unspecified, G98.0 — Neurogenic arthritis, not elsewhere classified, G98.8 — Other disorders of nervous system, +52 more

Principal diagnosis restriction (Medicare Code Editor)

Manifestation code — the underlying condition is sequenced first.

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Myasthenia Gravis without (Acute) Exacerbation and Other Myoneural Disorders) for risk-adjusted payment.

G70.00 — Myasthenia gravis without (acute) exacerbation, G70.1 — Toxic myoneural disorders, G70.2 — Congenital and developmental myasthenia, G70.80 — Lambert-Eaton syndrome, unspecified, G70.81 — Lambert-Eaton syndrome in disease classified elsewhere, G70.89 — Other specified myoneural disorders, G70.9 — Myoneural disorder, unspecified, G73.1 — Lambert-Eaton syndrome in neoplastic disease

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Myasthenia Gravis with (Acute) Exacerbation

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Myopathies).

G72.0 — Drug-induced myopathy, G72.1 — Alcoholic myopathy, G72.2 — Myopathy due to other toxic agents, G72.3 — Periodic paralysis, G72.41 — Inclusion body myositis [IBM], G72.49 — Other inflammatory and immune myopathies, not elsewhere classified, G72.81 — Critical illness myopathy, G72.89 — Other specified myopathies, G72.9 — Myopathy, unspecified, G73.1 — Lambert-Eaton syndrome in neoplastic disease, G73.7 — Myopathy in diseases classified elsewhere, M05.40 — Rheumatoid myopathy with rheumatoid arthritis of unspecified site, M05.411 — Rheumatoid myopathy with rheumatoid arthritis of right shoulder, M05.412 — Rheumatoid myopathy with rheumatoid arthritis of left shoulder, M05.419 — Rheumatoid myopathy with rheumatoid arthritis of unspecified shoulder, M05.421 — Rheumatoid myopathy with rheumatoid arthritis of right elbow, M05.422 — Rheumatoid myopathy with rheumatoid arthritis of left elbow, M05.429 — Rheumatoid myopathy with rheumatoid arthritis of unspecified elbow, M05.431 — Rheumatoid myopathy with rheumatoid arthritis of right wrist, M05.432 — Rheumatoid myopathy with rheumatoid arthritis of left wrist, +53 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Thyroid Stimulating Hormone (TSH)

Contextual Map

Every relationship of G73.3 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run G73.3 with these 2 related codes in Claim Check

Hierarchy

Code First

Referenced by Code First instructions

  • M62.84 — Sarcopenia[Code First](via G73.-): “disorders of myoneural junction and muscle disease in diseases classified elsewhere (G73.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2027

Referenced by Index etiology/manifestation pairs

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 196 — Myasthenia Gravis without (Acute) Exacerbation and Other Myoneural Disorders [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

MDC crossing

  • MDC 01 — Diseases and Disorders of the Nervous System[MDC crossing]: “Diseases and Disorders of the Nervous System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 8,919 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Nearest codes

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "G73.3 — Myasthenic syndromes in other diseases classified elsewhere." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/g73.3-myasthenic-syndromes-in-other-diseases-classified-elsewhere

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Myasthenic syndromes in other diseases classified elsewhere

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to G73.3 in its code family, with their registry titles.

View all codes in the G73 family