All codes
G337
G337 – Antidiuretic hormone response test
OHIP Diagnostic & Therapeutic Procedures Code — DIAGNOSTIC AND THERAPEUTIC PROCEDURES · Schedule of Benefits
Antidiuretic hormone response test including the 8 hour water deprivation test.
When to Use
- Use G337 when performing the formal 8-hour water deprivation test to differentiate between diabetes insipidus and psychogenic polydipsia.
- Apply this code when administering a formal diagnostic protocol to assess the patient's response to exogenous antidiuretic hormone (desmopressin) following water restriction.
Common Pitfalls
- Do not bill G337 for routine serum or urine osmolality checks; it is specifically intended for the comprehensive 8-hour deprivation protocol.
- Avoid billing G337 in conjunction with G338 (Water deprivation test) as they are duplicative; choose the code that best reflects the specific protocol performed.
- Billing G337 as a standalone service without documenting the specific 8-hour timeline and the associated serial osmolality measurements will lead to audit recovery.
Billing Tips
- Ensure the medical record clearly indicates the start and end times of the 8-hour deprivation period to justify the diagnostic procedure fee.
- You may bill an assessment code (e.g., A007) alongside G337 if a separate, identifiable clinical assessment is performed during the same encounter, subject to GP15 rules.
Provider Fee$16.95
Effective: April 1, 2025
Category
J. Diagnostic and Therapeutic Procedures
Subcategory
DIAGNOSTIC AND THERAPEUTIC PROCEDURES
Service Type
Diagnostic
Code Classes
Diagnostic and Therapeutic Procedures
As per the , all insured services must be documented in appropriate records to establish that: 1. an insured service was provided; 2. the service for which the account is submitted is the service that was rendered; and 3. the service was medically necessary.
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