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Official Description

Water load test

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

The water load test, designated by CPT® Code 89235, is a diagnostic procedure utilized to assess the body's ability to manage fluid balance. During this test, the patient is required to ingest a specific volume of water, calculated at 20-25 milliliters per kilogram of their body weight. This ingestion of water serves to challenge the kidneys' ability to excrete excess fluid. Following the water intake, urine output is meticulously measured to evaluate how effectively the body is processing and eliminating the ingested fluid. A key focus of this test is to identify conditions such as inappropriate antidiuretic hormone (ADH) syndrome, where the body may retain water excessively, leading to potential complications. The results of the water load test can provide critical insights into the patient's renal function and fluid regulation mechanisms, aiding healthcare professionals in diagnosing and managing various medical conditions related to fluid imbalance.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The water load test is indicated for patients who exhibit symptoms or conditions that may suggest issues with fluid retention or regulation. The following are specific indications for performing this test:

  • Inappropriate Antidiuretic Hormone Syndrome (SIADH) This condition is characterized by excessive secretion of antidiuretic hormone, leading to water retention and dilutional hyponatremia.
  • Assessment of Renal Function The test can help evaluate how well the kidneys are functioning in terms of fluid excretion and balance.
  • Fluid Retention Disorders Patients presenting with unexplained fluid retention may undergo this test to determine the underlying cause.

2. Procedure

The water load test involves several critical procedural steps to ensure accurate results. The following outlines the procedure in detail:

  • Step 1: Patient Preparation Prior to the test, the patient should be informed about the procedure and any necessary preparations, such as fasting or medication adjustments, if applicable. It is essential to ensure that the patient is in a stable condition and understands the importance of the test.
  • Step 2: Water Ingestion The patient is instructed to ingest a calculated volume of water, specifically 20-25 mL per kilogram of their body weight. This ingestion should occur within a specified time frame to standardize the test conditions.
  • Step 3: Urine Collection After the water ingestion, urine output is measured over a defined period, typically several hours. The volume of urine produced is collected and recorded to assess the kidneys' response to the fluid load.
  • Step 4: Data Analysis The collected urine output is analyzed to determine whether the kidneys are effectively excreting the excess fluid. This analysis helps in identifying any abnormalities in fluid retention or excretion.

3. Post-Procedure

After the completion of the water load test, the patient may be monitored for any immediate reactions or complications. It is important to assess the patient's overall condition and ensure they are stable. The results of the test will be reviewed, and further diagnostic or therapeutic steps may be recommended based on the findings. Patients should be informed about any follow-up appointments or additional tests that may be necessary to address the underlying conditions identified during the water load test.

Short Descr WATER LOAD TEST
Medium Descr WATER LOAD
Long Descr Water load test
Status Code Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC) 9 - Not Applicable
Multiple Procedures (51) 9 - Concept does not apply.
Bilateral Surgery (50) 9 - Concept does not apply.
Physician Supervisions 09 - Concept does not apply.
Assistant Surgeon (80, 82) 9 - Concept does not apply.
Co-Surgeons (62) 9 - Concept does not apply.
Team Surgery (66) 9 - Concept does not apply.
Diagnostic Imaging Family 99 - Concept Does Not Apply
APC Status Indicator Service Paid under Fee Schedule or Payment System other than OPPS
Type of Service (TOS) 5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS) none
MUE Not applicable/unspecified.
CCS Clinical Classification 235 - Other Laboratory
Date
Action
Notes
2011-01-01 Deleted Deleted
2004-01-01 Added Code added.
Code
Description
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