Abstract: PO1429
Water Load Test in the Diagnosis of Syndrome of Inappropriate Antidiuresis (SIAD): Results from the Waterline Study
Session Information
- Fluid, Electrolyte, and Acid-Base Disorders: Clinical - 1
October 22, 2020 | Location: On-Demand
Abstract Time: 10:00 AM - 12:00 PM
Category: Fluid, Electrolyte, and Acid-Base Disorders
- 902 Fluid, Electrolyte, and Acid-Base Disorders: Clinical
Authors
- Cohen, Raphael Rc, Hopital Europeen Georges-Pompidou Pole Cardio-vasculaire Renal Metabolique, Paris, Île-de-France, France
- Bouderlique, Elise, U1155 Inserm, Tenon Hospital, Paris, France
- Bureau, Côme, Hopital Europeen Georges-Pompidou Pole Cardio-vasculaire Renal Metabolique, Paris, Île-de-France, France
- Seervai, Riyad N. H., Center for Precision Environmental Health, Baylor College of Medicine, Houston, Texas, United States
- Blanchard, Anne, Hopital Europeen Georges-Pompidou Pole Cardio-vasculaire Renal Metabolique, Paris, Île-de-France, France
- Houillier, Pascal, Hopital Europeen Georges-Pompidou Pole Cardio-vasculaire Renal Metabolique, Paris, Île-de-France, France
- Vrigneaud, Laurence, Hopital Prive La Louviere, Lille, Nord-Pas-de-Calais, France
- Bertocchio, Jean-philippe, Hopital Europeen Georges-Pompidou Pole Cardio-vasculaire Renal Metabolique, Paris, Île-de-France, France
Group or Team Name
- Waterline study investigators
Background
SIAD is caused by an inadequate kidney reabsorption of water, mainly under the action of antidiuretic hormone. The latest international recommendations stated the diagnosis of SIAD relies on hypotonic hyponatremia with inadequate urine osmolality. Blood volume has to be normal, with adrenal, thyroid, and renal insufficiency excluded. These guidelines ruled out the usefulness of abnormal response to water load test (WLT) due to the lack of published evidence.
Methods
In the Waterline study (NCT04256499), we retrospectively analyzed data from patients who underwent a WLT (oral administration of 20 mL/kg of water) in our department.
Results
From 02/2001 to 10/2019, 173 adults were included. Out of them, 80(46%) had a SIAD and 21(12%) were considered ‘normal’, 72(42%) had hyponatremia of other origin. Among the SIAD patients, 33(41%) had a fasting plasma sodium (PNa) ≥135mM (‘normonatremic SIAD’), 47(59%) had ‘hyponatremic SIAD’: We found no differences in demographic data or medical history between these two groups. During WLT, ‘normonatremic SIAD’ patients behaved specifically by exerting hyponatremia (while normal individuals did not), resembling ‘hyponatremic SIAD’ patients (Figure 1). While their fasting urine osmolality (U-Osm) was initially higher, ‘normonatremic SIAD’ and ‘hyponatremic SIAD’ patients reached the same minimum U-Osm (389±257 vs. 350±202mOsm/kgH2O, p=0.76). Additionally, they reached a higher minimum value of PNa than ‘hyponatremic SIAD’ patients (132±2 vs. 127±3mM, p<0.0001). These results were confirmed in an independent cohort of 38 WLT where 24 (63%) were ‘normonatremic SIAD’.
Conclusion
We conclude that, without WLT, a diagnosis of SIAD could be missed in 40 to 63% of SIAD patients.
Figure 1. Evolution of PNa during WLT in normal (green), 'hyponatremic SIAD' (red), and 'normonatremic SIAD' (blue) patients.