FGF23 and vitamin D deficiency: On comparing 25 (OH) vitamin D deficient (< 37.5 nmol/L) and non-deficient (≥ 37.5 nmol/L) patients, those with 25 OH vitamin D deficiency had higher E-selectin (p = 0.047) and lower FGF23 (p = 0.013) compared to non-deficient patients (Table 2; Fig. 1a, b).