The disorders of water balance have seen both a change in nomenclature and new therapeutic options. Reflecting a 2022 international consensus, central diabetes insipidus is increasingly termed arginine vasopressin deficiency (AVP-D) and nephrogenic diabetes insipidus arginine vasopressin resistance (AVP-R) — partly to avoid dangerous confusion with diabetes mellitus. Diagnostically, the copeptin assay (a stable surrogate for AVP, measured after hypertonic saline or arginine stimulation) has markedly improved the accuracy of distinguishing AVP-D from primary polydipsia. Treatment of AVP-D remains desmopressin.
For the syndrome of inappropriate antidiuresis (SIAD), fluid restriction is first-line but frequently insufficient. The vasopressin-receptor antagonist tolvaptan effectively raises serum sodium (with careful monitoring for overcorrection and hepatotoxicity), and the notable emerging option is the SGLT2 inhibitor empagliflozin, which — by inducing osmotic diuresis — improved serum sodium when added to fluid restriction in a randomized trial, with possible neurocognitive benefit, representing a promising, better-tolerated adjunct.
Further reading: central diabetes insipidus diagnosis and management (Tomkins et al., JCEM 2022); syndrome of inappropriate antidiuresis (Warren et al., Endocrine Reviews 2023; Adrogué & Madias, NEJM 2023).