Water Load Test Value for Hyponatremia

Inclusion Criteria: * ≥ 18 years old at the time of the test * affiliated to a social insurance system * water load test performed at the Renal and Metabolic Diseases Unit of the European George Pompidou Hospital, AP-HP, Paris, France * between 01/01/2001 and 12/31/2019 Exclusion Criteria: * hypernatremia and/or polyuria-polydipsia (diabetes insipidus) * hyponatremia due to a tea and toast syndrome and/or a beer potomania * hyponatremia due to a high (or normal) osmolality related to diabetes mellitus, hyperproteinemia and/or intoxication * chronic kidney disease with an estimated glomerular filtration rate (eGFR) by the MDRD formula \<60 mL/min/1.73m2 * hyponatremia related to thiazides * hyponatremia related to an hypovolemic status * syndrome of inappropriate antidiuresis related to an endocrine disorder (such as hypothyroidism or adrenal insufficiency)