G70.00
BillableMyasthenia gravis without (acute) exacerbation
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G70.00 an HCC code?
Yes. G70.00 maps to Myasthenia Gravis/Myoneural Conditions and Guillain-Barre under the CMS-HCC V28 risk adjustment model (and Myasthenia Gravis/Myoneural Conditions and Guillain-Barre Syndrome under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for G70.00
For G70.00 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed G70.00 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G70.00 is the ICD-10-CM diagnosis code for myasthenia gravis without (acute) exacerbation. A chronic autoimmune condition where muscles become weak and tire easily because the immune system interferes with nerve-muscle communication, currently without acute worsening. G70.00 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering diseases of myoneural junction and muscle (g70-g73).
Under the CMS-HCC V28 risk adjustment model, G70.00 maps to Myasthenia Gravis/Myoneural Conditions and Guillain-Barre (HCC 196) with a community, non-dual, aged base RAF weight of 0.402. Under the older CMS-HCC V24 model, G70.00 maps to Myasthenia Gravis/Myoneural Conditions and Guillain-Barre Syndrome (HCC 75) with a community, non-dual, aged base RAF weight of 0.425. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Distinguish between G70.00 (without exacerbation) and G70.01 (with exacerbation) based on current clinical status. Because G70.00 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for G70.00 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Distinguish between G70.00 (without exacerbation) and G70.01 (with exacerbation) based on current clinical status
- •Document muscle weakness patterns and any recent changes in symptoms to support appropriate code selection
Clinical Significance
Myasthenia gravis without acute exacerbation is a chronic autoimmune neuromuscular disorder that requires lifelong immunosuppressive therapy, cholinesterase inhibitors, and regular monitoring. It significantly impacts daily functioning through fluctuating muscle weakness. As a high-value HCC code in both V24 and V28, accurate capture is critical for reflecting the ongoing treatment costs and care complexity of these patients.
Documentation Requirements
- ✓Confirmed diagnosis of myasthenia gravis: positive acetylcholine receptor or anti-MuSK antibodies
- ✓Current disease status: stable, controlled, not in acute exacerbation
- ✓Pattern of muscle weakness: ocular, bulbar, generalized
- ✓Current medication regimen: pyridostigmine, immunosuppressants, corticosteroids
- ✓Functional status assessment: swallowing, respiratory function, daily activity limitations
- ✓Provider's explicit documentation of myasthenia gravis without exacerbation
Commonly Confused Codes
- •G70.01 — Myasthenia gravis with acute exacerbation is for worsening symptoms, crisis, or decompensation; use G70.00 when stable
- •G70.2 — Congenital and developmental myasthenia is present from birth and has a different pathophysiology (non-autoimmune)
- •G70.80 — Lambert-Eaton syndrome is a different autoimmune neuromuscular disorder with distinct antibody profile and treatment
- •G70.9 — Myoneural disorder, unspecified should never be used when myasthenia gravis is specifically documented