| [ Summary ] |
The common diseases in which vitamin D deficiency is observed frequently are diabetes and chronic kidney disease (CKD). Other risk factors are inadequate sunlight exposure and high body mass index. Even in early stages of CKD, fibroblast growth factor 23 is increased leading to low 1-alpha hydroxylase activity in the proximal tubules. If CKD is accompanied with diabetes or moderate proteinuria, its substrate 25-hydroxyvitamin D (25D) is reduced resulting in low 1,25-dihydroxyvitamin D (1,25D) levels. The observed association between early CKD and increased fracture rate can be partly explained by the deficiencies in 1,25D, because it is indispensable not only for bone integrity but for muscle strength that is associated with falls. |