Arginine vasopressin deficiency: towards a better characterization.

Arginine vasopressin (AVP) deficiency, previously termed central diabetes insipidus, arises from impaired AVP synthesis or secretion by the hypothalamus and/or the posterior pituitary gland and presents with hypotonic polyuria and polydipsia. To differentiate AVP deficiency from AVP resistance and primary polydipsia, a stepwise diagnostic workup is required. In recent years, copeptin, as a reliable surrogate marker of AVP secretion, has been incorporated into diagnostic algorithms, and copeptin-based stimulation tests have substantially improved diagnostic accuracy. Once AVP deficiency has been established, identification of the underlying cause is essential. A wide range of etiologies, including neurosurgical and traumatic injuries, granulomatous, inflammatory and autoimmune diseases, vascular events, infections, and genetic defects, require a diagnostic approach tailored to the suspected diagnosis. Evaluation should include a careful assessment of the patient's personal and family history, clinical examination, laboratory studies, imaging and, when indicated, tissue biopsy. In patients with apparently idiopathic AVP deficiency, a careful longitudinal follow-up is warranted, since it may represent the first manifestation of an underlying pathology. Treatment of AVP deficiency consists of desmopressin replacement combined with etiology-specific management.