ALB and chronic kidney disease: In the CKD stage 4 group serum 25(OH)D was 19.15 (IQR 13.6-23.4) ng/mL, whereas in the CKD stage 5 group it was 10.95 (IQR 9.3, 16.4) ng/mL (p = 0.006); the Authors also observed a significant negative correlation between urine albumin-to-creatinine ratio (ACR) and 25(OH)D (p = 0.002) (Table 3).