FGF23 and endothelial dysfunction: Some studies have also shown a positive relationship between FGF23 concentration and insulin resistance [70,71] and an association of FGF23 circulating levels with endothelial dysfunction, vascular calcification, left ventricular hypertrophy and incidence of mortality and cardiovascular events in the general population [72], although low levels of 25OHD are usually also associated with these occurrences [73].