2026 ICD-10-CM Diagnosis Code G73.3Myasthenic syndromes in other diseases classified elsewhere
ICD-10-CM Codes›G00–G99›G70-G73›G73
- Billable — Valid for Submission
- Not Chronic
G73.3 is a billable ICD-10-CM diagnosis code for myasthenic syndromes in other diseases classified elsewhere. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is a manifestation code that cannot be reported as the principal diagnosis. Coders also document this condition as myasthenic syndrome due to another disorder. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Myopathies.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for G73.3.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Myasthenic syndrome due to another disorder
- Myasthenic syndrome due to hypothyroidism
- Myasthenic syndrome due to pernicious anemia
- Myasthenic syndrome due to thyrotoxicosis
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Code First
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Myasthenia Gravis
Myasthenia gravis, sometimes called MG, is a chronic (long-lasting) disease that causes weakness in your voluntary muscles. The voluntary muscles are the ones that you can control. They include the muscles you use for:
The full article covers:
- What is myasthenia gravis?
- What causes myasthenia gravis?
- Who is more likely to develop myasthenia gravis?
- What are the symptoms of myasthenia gravis?
- How is myasthenia gravis diagnosed?
- What are the treatments for myasthenia gravis?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert G73.3 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About G73.3Overview
Is G73.3 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report myasthenic syndromes in other diseases classified elsewhere on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Can G73.3 be a principal diagnosis?
No. This is a manifestation code: myasthenic syndromes in other diseases classified elsewhere describes the manifestation of an underlying disease rather than the disease itself, so the underlying condition is sequenced first.
What is the ICD-9 equivalent of G73.3?
Under the General Equivalence Mappings, myasthenic syndromes in other diseases classified elsewhere converts to ICD-9-CM 358.1 (myasthenia in oth dis). The mapping is a direct match.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
