T57.3X4A: Toxic effect of hydrogen cyanide, undetermined, initial encounter
T57.3X4A, toxic effect of hydrogen cyanide, undetermined, initial encounter, is listed as a covered diagnosis in 3 Medicare billing and coding articles that apply to 12 HCPCS Level II codes, including G0238 (Therapeutic procedures to improve respiratory function…), G0237 (Therapeutic procedures to increase strength or endurance…), G0239 (Therapeutic procedures to improve respiratory function or…). The articles come from 2 Medicare contractors. A listed diagnosis supports medical necessity only; coverage still depends on the LCD's criteria and on documentation in the medical record.
HCPCS Level II codes with T57.3X4A as a covered diagnosis
| Code | Description | Medicare coverage | DMEPOS fee 2026 (state range) | Articles listing it |
|---|---|---|---|---|
| G0238 | Therapeutic procedures to improve respiratory function, other than described by g0237, one on one, face to face, per 15 minutes (includes monitoring) | Carrier judgment | — | 2 |
| G0237 | Therapeutic procedures to increase strength or endurance of respiratory muscles, face to face, one on one, each 15 minutes (includes monitoring) | Carrier judgment | — | 2 |
| G0239 | Therapeutic procedures to improve respiratory function or increase strength or endurance of respiratory muscles, two or more individuals (includes monitoring) | Carrier judgment | — | 2 |
| G2187 | Patients with clinical indications for imaging of the head: head trauma | Carrier judgment | — | 1 |
| G2188 | Patients with clinical indications for imaging of the head: new or change in headache above 50 years of age | Carrier judgment | — | 1 |
| G2189 | Patients with clinical indications for imaging of the head: abnormal neurologic exam | Carrier judgment | — | 1 |
| G2190 | Patients with clinical indications for imaging of the head: headache radiating to the neck | Carrier judgment | — | 1 |
| G2191 | Patients with clinical indications for imaging of the head: positional headaches | Carrier judgment | — | 1 |
| G2192 | Patients with clinical indications for imaging of the head: temporal headaches in patients over 55 years of age | Carrier judgment | — | 1 |
| G2193 | Patients with clinical indications for imaging of the head: new onset headache in pre-school children or younger (<6 years of age) | Carrier judgment | — | 1 |
| G2194 | Patients with clinical indications for imaging of the head: new onset headache in pediatric patients with disabilities for which headache is a concern as inferred from behavior | Carrier judgment | — | 1 |
| G2195 | Patients with clinical indications for imaging of the head: occipital headache in children | Carrier judgment | — | 1 |
Medicare policy articles listing T57.3X4A
- A56717: Billing and Coding: Respiratory Therapy (Respiratory Care) (Palmetto GBA (MAC - Part A); 3 Level II codes). LCD with the same title: L34430
- A57224: Billing and Coding: Respiratory Care (Noridian Healthcare Solutions, LLC (MAC - Part A, MAC - Part B); 3 Level II codes). LCD with the same title: L34149
- A56612: Billing and Coding: CT of the Head (Palmetto GBA (MAC - Part A, MAC - Part B); 9 Level II codes). LCD with the same title: L34417
A diagnosis listed as covered in a billing and coding article supports medical necessity for the article's codes; it does not guarantee payment. Coverage depends on the LCD's criteria, the contractor's jurisdiction and documentation in the medical record.
Other T57 diagnoses (Toxic effect of other inorganic substances)
- T57.3X1A — Toxic effect of hydrogen cyanide, accidental (unintentional)…
- T57.3X2A — Toxic effect of hydrogen cyanide, intentional self-harm, initial…
- T57.3X3A — Toxic effect of hydrogen cyanide, assault, initial encounter
Frequently asked questions
Does Medicare cover T57.3X4A (Toxic effect of hydrogen cyanide, undetermined, initial…)?
Medicare covers items and services, not diagnoses. 3 Medicare billing and coding articles list T57.3X4A as a covered diagnosis for 12 HCPCS Level II codes: the diagnosis can support medical necessity for those codes, but payment still depends on the LCD's coverage criteria and the medical record.
Which HCPCS codes can be billed with ICD-10 T57.3X4A?
The Level II codes from the policies most specific to this diagnosis are G0238 (Therapeutic procedures to improve respiratory function…, 2 articles); G0237 (Therapeutic procedures to increase strength or endurance…, 2 articles); G0239 (Therapeutic procedures to improve respiratory function or…, 2 articles); G2187 (Patients with clinical indications for imaging of the…, 1 article); G2188 (Patients with clinical indications for imaging of the…, 1 article). Code choice depends on the item supplied; check each code's descriptor.
Which Medicare policy articles list T57.3X4A?
A56717 (Billing and Coding: Respiratory Therapy (Respiratory Care)); A57224 (Billing and Coding: Respiratory Care); A56612 (Billing and Coding: CT of the Head).
What is ICD-10-CM code T57.3X4A?
T57.3X4A is the ICD-10-CM code for toxic effect of hydrogen cyanide, undetermined, initial encounter, in category T57 (Toxic effect of other inorganic substances), chapter 19: Injury, poisoning and other consequences of external causes.
Next steps
- Run a reimbursement report for a device billed under G0238
- Watch G0238 for fee, coverage and descriptor changes
- Build a full Medicare revenue model for G0238
Sources: CMS Medicare Coverage Database billing and coding articles (covered ICD-10 code lists and HCPCS links); ICD-10-CM FY2026; CMS HCPCS Level II release October 2026; CMS DMEPOS fee schedule 2026 (non-rural state fees). Not billing or legal advice.
Chapter 19: Injury, poisoning and other consequences of external causes · All diagnoses · HCPCS lookup