Background. One of the disorders reflecting the pathology of water-electrolyte balance is polyuria-polydipsia syndrome. The most well-known forms of this syndrome include central and nephrogenic diabetes insipidus and primary polydipsia. Accurate verification of the diagnosis in patients with polyuria-polydipsia syndrome is a complex and labor-intensive process. A particular problem for clinicians is the combination of various forms of this syndrome, as well as its combination with electrolyte imbalance, including hyponatremia. One of the little-known causes of hyponatremia is reset osmostat syndrome. The article describes a clinical case of a possible combination of nephrogenic diabetes insipidus with primary polydipsia in a patient, while the presence of reset osmostat syndrome was not excluded.

Keywords: reset osmostat syndrome, polyuria-polydipsia syndrome, primary polydipsia, nephrogenic diabetes insipidus, hyponatremia