POLYUROPOLYDIPSIC SYNDROMES

Prognosis: Intracellular dehydration is the major risk in case of a po lyuropolydipsic syndrome. Excepting osmotic polyuria, prognosis depend s on a possibly progressive functional anomaly of the hypothalamopitui tary axis. Pathophysiology: Polyuropolydipsia occurs when antidiuretic hormone (ADH) secretion is absent (central diabetes insipidis), the k idney does not respond to ADH (nephrogenic diabetes insipidus) or in c ase of physiological inhibition of ADH secretion (primary polydipsia). Exploration: Dynamic explorations are associated with radioimmunoassa y of ADH. They are particularly useful in case of atypical diabetes in sipidus and include the water restriction test and a study of the sens itivity to exogenous ADH (dDAVP). The results orient the etiologic dia gnosis and allow an evaluation of the fluid intake required as a funct ion of the maximal concentrating capacity of the kidneys. Treatment of central diabetes insipidus: Treatment is based on ADH analogs (dDAVP) . The aim is to obtain a constant antidiuretic effect without hyponatr emia or escape. In case oi partial central diabetes insipidus, a non-h ormone treatment using compounds which increase vasopressin release or its effect on the kidney can be proposed.