Risk of hypertension and heart failure linked to high-normal serum sodium and tonicity https://academic.oup.com/eurjpc/advance-article/doi/10.1093/eurjpc/zwaf232/8110965 A serum sodium and tonicity exceeding 140 mmol/L and 287 mosmol/kg are associated with increased risk of hypertension and heart failure https://www.t-online.de/gesundheit/aktuelles/id_100762138/natriumwert-obere-norm-gefaehrdet-herz-studie-deckt-risiko-auf.html