A COMBINED OUTPATIENT AND INPATIENT OVERNIGHT WATER DEPRIVATION TEST IS EFFECTIVE AND SAFE IN DIAGNOSING PATIENTS...

Area of Science:

• Endocrinology
• Nephrology
• Internal Medicine

Background:

• The polyuria-polydipsia syndrome (PPS) presents a diagnostic challenge, often requiring the water deprivation test (WDT) for differential diagnosis.
• Traditional WDT can be inconvenient and may lack precision in distinguishing partial central diabetes insipidus (pCDI) from primary polydipsia (PP).
• Existing diagnostic methods necessitate a comprehensive approach, especially for complex cases of PP and pCDI.

Purpose of the Study:

• To evaluate the feasibility and safety of a combined outpatient and inpatient overnight water deprivation test (WDT) protocol for diagnosing PPS.
• To assess the diagnostic accuracy of the WDT protocol in differentiating between primary polydipsia (PP) and various forms of diabetes insipidus (DI).

Main Methods:

• A retrospective analysis of clinical data and laboratory results from 52 patients with PPS undergoing WDT.
• Inclusion of an overnight unsupervised period within the WDT protocol.
• Measurement of serum osmolality, urine osmolality, urine-to-serum osmolality ratio, and vasopressin (AVP) levels.

Main Results:

• Primary polydipsia (PP) was the most frequent diagnosis, followed by complete central DI (cCDI), partial central DI (pCDI), and nephrogenic DI (NDI).
• Over 90% of patients demonstrated an expected increase in serum osmolality post-dehydration.
• Post-dehydration urine osmolality and urine-to-serum osmolality ratio significantly differentiated most groups (P<.05), while AVP levels distinguished cCDI and NDI.

Conclusions:

• A combined outpatient and inpatient overnight WDT protocol is safe and feasible in experienced centers with careful execution.
• The WDT, alongside vasopressin (AVP) levels, aids in differentiating PPS subtypes but may require a comprehensive diagnostic strategy.
• Advancements in diagnostic tools are anticipated to enhance the accuracy of PPS diagnosis in the future.