G70.1 ICD-10-CM Code: Toxic myoneural disorders
G70.1 maps to CMS-HCC V28 196 (RAF 0.516). Documentation must support MEAT. MEAT criteria · RAF calculator · free HCC coding tools
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FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Diseases of myoneural junction and muscle (G70-G73)
G70.1
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceToxic myoneural disorders
Muscle weakness and dysfunction caused by exposure to toxic substances that damage the connection between nerves and muscles.
Buddy Insight
Toxic myoneural disorders represent damage to the neuromuscular junction caused by toxic substances such as organophosphates, botulinum toxin, or certain medications.
CMS-HCC V28
MappedHCC 196
RAF 0.516
CMS-HCC V24
MappedHCC 75
RAF 0.472
ACA/HHS
MappedHCC 115
Varies by metal level
ESRD/PACE
MappedHCC 75
RAF 0.074
RXHCC
MappedHCC 153
RAF 1.094
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for G70.1 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for G70.1 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for G70.1 in this effective period.
Excludes 1
Official- botulism (A05.1, A48.51-A48.52)
- transient neonatal myasthenia gravis (P94.0)
Code First
Official- (T51-T65) to identify toxic agent
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for G70.1 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for G70.1 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is G70.1 an HCC code?
Yes. G70.1 (Toxic myoneural disorders) maps to Myasthenia Gravis without (Acute) Exacerbation and Other Myoneural Disorders under the CMS-HCC V28 risk adjustment model (and Myasthenia Gravis/Myoneural Disorders and Guillain-Barre Syndrome/Inflammatory and Toxic Neuropathy under V24), with a community non-dual aged RAF of 0.516. It is billable for payment year 2026.
Coder answer: G70.1 is billable and maps to V28 HCC 196, Myasthenia Gravis without (Acute) Exacerbation and Other Myoneural Disorders. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- G70.1
- Description
- Toxic myoneural disorders
- HCC (V28)
- HCC 196 — Myasthenia Gravis without (Acute) Exacerbation and Other Myoneural Disorders
- RAF
- 0.516
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. 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.
Work G70.1 in the Code Book — tabular path, V28 RAF, and MEAT checklist →
MEAT Criteria for G70.1
For G70.1 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 G70.1 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
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What This Code Means
G70.1 is the ICD-10-CM diagnosis code for toxic myoneural disorders. Muscle weakness and dysfunction caused by exposure to toxic substances that damage the connection between nerves and muscles. G70.1 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, G70.1 maps to Myasthenia Gravis without (Acute) Exacerbation and Other Myoneural Disorders (HCC 196) with a community, non-dual, aged base RAF weight of 0.516. Under the older CMS-HCC V24 model, G70.1 maps to Myasthenia Gravis/Myoneural Disorders and Guillain-Barre Syndrome/Inflammatory and Toxic Neuropathy (HCC 75) with a community, non-dual, aged base RAF weight of 0.472. 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.
Document the specific toxic agent when possible (e.g., organophosphates, heavy metals, medications). Because G70.1 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 G70.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the specific toxic agent when possible (e.g., organophosphates, heavy metals, medications)
- •Verify that the myoneural disorder is directly related to toxin exposure rather than another etiology
Clinical Significance
Toxic myoneural disorders represent damage to the neuromuscular junction caused by toxic substances such as organophosphates, botulinum toxin, or certain medications. These conditions can be acutely life-threatening due to respiratory muscle paralysis. Accurate coding captures the severity of the toxic exposure and the specialized care required for neuromuscular recovery.
Documentation Requirements
- ✓Identification of the specific toxic agent causing the myoneural disorder
- ✓Clinical evidence of neuromuscular junction dysfunction: weakness, fatigability, respiratory compromise
- ✓Electrodiagnostic studies showing neuromuscular transmission defect when available
- ✓Temporal relationship between toxic exposure and symptom onset
- ✓Treatment administered: antidotes, supportive care, respiratory support
- ✓Provider's explicit diagnosis linking the myoneural disorder to toxic exposure
Commonly Confused Codes
- •G70.00/G70.01: Myasthenia gravis is autoimmune in origin, not toxic; do not confuse with toxic myoneural disorders
- •G62.0: Drug-induced polyneuropathy affects peripheral nerves, not the neuromuscular junction
- •T65.94XA: Toxic effect of unspecified substance captures the exposure itself, not the resulting myoneural disorder
- •G70.89: Other specified myoneural disorders is for non-toxic causes