Protocolo diagnóstico de la poliuria

Polyuria is defined as a urinary excretion volume > 3 l/24 h or > 40-50 ml/kg/24 h. It is essential to differentiate it from symptoms such as nocturia and pollakiuria that are related to urologic pathology. To guide the diagnosis it is important to differentiate whether it is an osmotic or aqueous polyuria. The most frequent cause of osmotic diuresis is decompensated diabetes mellitus. The main causes of aqueous polyuria are primary polydipsia (PP), vasopressin deficiency (AVP-D) and vasopressin resistance (AVP-R). Making an accurate diagnosis of the different causes of polyuria is essential because the therapeutic plan varies. Once aqueous polyuria is confirmed, the cause of the polyuria-polydipsia syndrome must be established. Currently, it is recommended to start the study with a basal copeptin measurement to differentiate AVP-D from AVP-R and to differentiate AVP-D from PP to measure stimulated copeptin after infusion of arginine or hypertonic saline.