Clinical Syndromes Associated with Hypovasopressinism

Abstract

Clinical syndromes associated with absolute or relative hyposecretion of vasopressin and/or with diminished renal responsiveness to the antidiuretic effect of the hormone (hypovasopressinism) are usually classified in four main classes depending on the nature of the primary defect (Table 17.1). Each of the four syndromes is the end result of several pathogenetic mechanisms and can have diverse etiologies. In the first two of them — central diabetes insipidus (GDI) and nephrogenic diabetes insipidus (NDI) — the underlying disturbance is a diminished response of the AVP secretion mechanism to physiological stimuli, or a diminished renal response to hydroosmotic action of AVP respectively; this is manifested by solute-free polyuria and secondary polydipsia. In the other two — polydipsic diabetes insipidus (PDI) and essential hypernatremia (EH) — the clinical picture is determined by the primary disturbance of thirst osmoregulation, but hypovasopressinism is also involved, at least secondarily, in the abnormalities associated with these syndromes.