It consists of the vitamin D binding protein (VDBP)-bound 25(OH)D, albumin-bound 25(OH)D, and free 25(OH)D, and they may be influenced by ethnicity, religion, sunlight exposure, and several conditions altering vitamin D metabolism, such as obesity, drugs, and diabetes, in addition to CKD [9,10]. Here, GC is linked to obesity due to melanocortin 4 receptor deficiency.