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Billing code

G337A — Antidiuretic Hormone Response Test Including The 8 Hour Water Deprivation Test

Water deprivation test

Bill G337 for an antidiuretic hormone response test, including the 8-hour water deprivation test.

Watch for: The water deprivation test is included; don't bill it separately.

Code

G337A

Description

Antidiuretic Hormone Response Test Including The 8 Hour Water Deprivation Test

FHO+ basket

Not in the FHO+ base rate basket (Schedule 2 or 2B).

Effective date

Apr 1, 2025

Termination date

No end date

Explanation

Updated October 26, 2026

Antidiuretic hormone response test, including the 8-hour water deprivation test.

What it covers

G337 is an antidiuretic hormone response test, and includes the 8-hour water deprivation test (J41).

The hypertonic saline infusion test is listed separately as G341 (J41).

Billing rules

• The 8-hour water deprivation test is included and not billed separately (J41).
• Payable in addition to a consultation or assessment unless listed as included (J3).
• Includes preparing the patient, doing the test with monitoring afterwards, interpreting results with a written report to the referring provider where appropriate, and follow-up arrangements (J3).
• Marked (+): when the test is the sole reason for the visit, add G700 once per visit. G700 is not payable in hospital, and not when you are also paid a consultation or assessment that day and have a financial interest in the facility (J3).
• For a patient enrolled with a capitation-based group, G700 pays 15% of its fee (J3).

Often billed with

• G700 basic fee-per-visit premium when the test is the only reason for the visit, outside hospital (J3).

Related codes: G341, G493, G497, G700

Source: Schedule of Benefits (July 1, 2026), Diagnostic and Therapeutic Procedures, Endocrinology and Metabolism, page J41; preamble J3.

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