For chronic hyponatremia (6+ months) by way of siadh, when should this condition stop and what other treatments are there besides water restriction, salt, urea, democyclocine and tolvaptan? thank you?

SIADH is a paraneoplastic syndrome which is often caused by a malignant disease, usually a solid malignant tumor and lung cancer is the most common cause of this paraneoplastic syndrome. The therapeutic measures you mentioned deal with the effect of high ADH but not treating the cause of SIADH. If the malignant disease can be treated, SIADH will be cured.