Chronic Kidney Disease and Vitamin D

The ideal concentration of 25(OH)D and its thresholds for deficiency or insufficiency in chronic kidney disease (CKD) are not well established; however, it can be considered the same as in the population without CKD. It is suggested that it is more accurate to define CKD patients ' vitamin D levels as inadequate rather than deficient/insufficient. The prevalence of vitamin D inadequacy is more common in CKD patients and the hydroxylation and activation of vitamin D decreases according to the decrease of glomerular filtration rate (GFR). In general, in CKD patients, vitamin D deficiency or insufficiency should be corrected using the therapeutic strategies used in the general population. There are some guidelines that specify the most adequate vitamin D treatment according to the CKD stage. In these guidelines, in stages 1-2, may be followed the indications for the general population. In stages 3-4, vitamin D2 or D3 can be used and if there is also secondary hyperparathyroidism, prolonged-release calcifediol should be used. In stages 4-5 with severe and progressive secondary hyperparathyroidism or in cases of secondary hyperparathyroidism associated with mineral and bone disease, some authors recommend that calcitriol or vitamin D analogues should be used. For stage 5 non-dialyzed patients, calcitriol or vitamin D analogues are recommended, but some authors suggest calcimimetics alone or in combination therapy. For stage 5 dialyzed patients, the therapeutic choice must be individualized and decided according to the patient's concomitant medication. In cases of kidney transplantation (in the first 12 months), active vitamin D and/or anti-resorptive drugs are recommended, if GFR is superior to 30 mL/min/1.73 m2 with low bone mineral density. The vitamin D treatment benefits should be weighed together against its potential adverse effects. Serum calcium, phosphorus, 25(OH)D, PTH and alkaline phosphatase should always be monitored in the beginning and during the treatment.