Humayun MA, et al. - Here, researchers audited the local guidelines for in-patient tolvaptan use in SIADH. They recognized that Tolvaptan was safe and effective in the treatment of SIADH-related significant, symptomatic hyponatraemia when used under specialist guidance and strict monitoring. A sodium level relapsing below the treatment threshold by 1 week after discontinuation was a valid indicator of a patient group with re-treatment/longer-term therapy needs, all of whom had underlying malignancy. In addition, the criteria set locally for initiating Tolvaptan use identified a group where they recommended considering further investigation for underlying malignancy.