Hypernatremia and subclinical chronic kidney disease
In the Atherosclerosis Risk in Communities (ARIC) study, serum sodium >142 mmoL is a risk factor for LVH and heart failure in middle-aged (45–66 years) persons with a 25-year follow-up. In the absence of water ingestion during the night, the key determinant of morning serum sodium concentration is the urine concentration capacity of the kidneys. A urine concentration defect (i.e. partial nephrogenic diabetes insipidus) is an early feature of chronic kidney disease (CKD), a known cause of LVH and heart failure. CKD may be diagnosed in persons with preserved glomerular filtration rate (GFR) when there is other evidence of kidney injuries, such as albuminuria or electrolyte and other abnormalities due to underlying tubular disorders, among others.5 In this regard, higher morning serum sodium secondary to a nephrogenic urine concentration defect would be diagnostic of CKD if persistent for longer than 3 months, even if GFR is normal. Urine concentration defects will lead to nocturia, as lack of water ingestion during the night will not be compensated by decreased urine volume, in turn leading to higher morning serum sodium due to excess water losses in urine during the night.

Source: https://academic.oup.com/eurheartj/advance-article/doi/10.1093/eurheartj/ehac367/6649067?rss=1&login=true