The problem of differential diagnosis and treatment of polyuria–polydipsia syndrome

In this clinical example, attention is focused on the features of differential diagnosis in order to verify the diagnosis in the group of diseases of diabetes insipidus and the use of vasopressin analogs for the treatment. It should be noted that central diabetes insipidus (CDI), nephrogenic diabetes insipidus (NDI) and primary polydipsia/dipsogenic diabetes insipidus have similar clinical manifestations, but different causes and, accordingly, different approaches to treatment. With primary polydipsia, there is no deficiency or decrease in the action of antidiuretic hormone (ADH), unlike CND/NND, but there is a decrease in the sensitivity of the thirst center (thirst bothers the patient even with a low level of electrolytes), and increased fluid intake is associated with a compulsive desire to drink on the background of psychiatric diseases. Thus, in primary polydipsia, polyuria is a consequence of polydipsia, in contrast to CDI and NDI, where polyuria induces polydipsia. The appointment of desmopressin is justified only in cases of proven ADH deficiency, and in the absence of indications, it can lead to critical conditions up to death.