Prevailing clinical hyponatremia guidelines, protocols and flowcharts employ this principle by postulating that hyponatremia with a Ou value >100 mOsmol/kg or a Ou value higher than the plasma osmolality (Op) should suggest a monofactorial diagnosis of inappropriate AVP release (Ter Maaten et al., 2017–2021; Hoorn et al., 2014; Hoorn & Zietse, 2017; Sterns et al., 2022; Workeneh et al., 2023). This evidence concerns the gene AVP and Hyponatremia.