Table 3: Comparisons between patients' subgroups regarding vitamin D deficiency (< 20 ng/ml).

Vitamin D HF + RF HF RF Chi-square test
No. % No. % No. % X2 P-value
Deficient 29 96.70% 13 43.30% 23 76.70% 21.711 < 0.001
Normal level 1 3.30% 17 56.70% 7 23.30%