Redefining Diagnostic Cut‐Offs for the Indirect Water Deprivation Test
Authors' conclusion
This study demonstrates that a serum sodium cut-off of ≥ 148 mmol/L in tandem with urine osmolality yields the best diagnostic accuracy to differentiate between AVP-D, AVP-R, and PP. Serum sodium may be more reliable than serum osmolality in the investigation of patients with PPS, demonstrating lower biological and analytical variability.
Study context
- Population
- Patients with polydipsia polyuria syndrome who underwent a water deprivation test, August 2014 to August 2023
- Participants
- 135 patients
- Comparison
- Serum sodium vs serum osmolality cut-offs in the water deprivation test
- Outcome
- Diagnostic accuracy to differentiate AVP-D, AVP-R and PP
Methodological detailsretrospective
- Retrospective
Performance
As reported in the abstract
- Standard serum osmolality cut-off ≥ 300 mOsm/kg: sensitivity
- 76.19%
- Standard serum osmolality cut-off ≥ 300 mOsm/kg: specificity
- 76.92%
- Serum sodium cut-off ≥ 148 mmol/L: specificity in excluding primary polydipsia (PP)
- 100%
- Serum sodium ≥ 148 mmol/L with urine osmolality > 630 mOsm/kg (PP) and < 383 mOsm/kg (AVP-D/AVP-R), plus review of post-desmopressin urine osmolality and clinical monitoring in equivocal cases (n = 6): sensitivity within the study sample
- 100%
- Same approach: specificity within the study sample
- 100%
Further findings
Variability · lower with serum sodium
reduction 37.5% · P < 0.001
Original publication
Redefining Diagnostic Cut‐Offs for the Indirect Water Deprivation Test. Clin Endocrinol (Oxf). Published 5 December 2024. doi:10.
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