RESUMEN
PURPOSE: We checked the levels of serum 25-hydroxyvitmain D (25OHD) in the patients with chronic kidney disease (CKD) to survey the status of vitamin D levels, to see the seasonal variations of 25OHD, and to evaluate the relationships among the levels of intact PTH, corrected calcium, and phosphorus. METHODS: We defined vitamin D insufficiency and vitamin D deficiency as serum 25-hydroxyvitamin D levels between 20 and 30 ng/mL and below 20 ng/mL, respectively. 185 patients in a single center were enlisted who categorized into 3 groups, CKD2-3, CKD4, and CKD5 by eGFR using MDRD7 equation. To see the seasonal differences of the levels of 25OHD, we collected laboratory data two times per each patient during summer division (April to September) and winter division (October to March). RESULTS: Prevalences of hypovitaminosis D were 42.8% (CKD2-3), 66.1% (CKD4), 92.8% (CKD5) in summer division and 48.7% (CKD2-3), 73.1% (CKD4), 92.8% (CKD5) in winter division. Seasonal difference of the levels of 25OHD was evident only in CKD stage 2-3 (p=0.018). Negative correlations were recognized between 25OHD and intact PTH (r=-0.2048, p<0.001), phosphorus (r=-0.1711, p=0.0011). CONCLUSION: Hypovitaminosis D is prevalent even in patients with early stages of CKD. The levels of 25OHD decreased significantly in winter division in patients with CKD stages 2-3. The levels of 25OHD were inversely correlated with those of intact PTH, phosphorus, respectively.