Background: Previous studies have shown that treatment with ergocalciferol in patients with CKD stage 3 + 4 is\nnot effective with less than 33% of patients achieving a 25-OH vitamin D target of >30 ng/ml. The aim of this study\nwas to test the response to cholecalciferol in CKD. We attempted to replete 25-OH vitamin D to a target level of\n40ââ?¬â??60 ng/ml using the response to treatment and PTH suppression as an outcome measure.\nMethods: This retrospective cohort study identified patients (Stages 2ââ?¬â??5 and Transplant) from 2001ââ?¬â??2010 who\nregistered at the Chronic Kidney Disease Clinic. Patients received cholecalciferol 10,000 IU capsules weekly as initial\ntherapy. When levels above 40 ng/ml were not achieved, doses were titrated up to a maximum of 50,000 IU\nweekly. Active vitamin D analogs were also used in some Stage 4ââ?¬â??5 CKD patients per practice guidelines. Patients\nreaching at least one level of 40 ng/mL were designated RESPONDER, and if no level above 40 ng/mL they were\ndesignated NON-RESPONDER. Patients were followed for at least 6 months and up to 5 years.\nResults: 352 patients were included with a mean follow up of 2.4 years. Of the CKD patients, the initial 25-OH\nvitamin D in the NON-RESPONDER group was lower than the RESPONDER group (18 vs. 23 ng/ml) (p = 0.03).\nAmong all patients, the initial eGFR in the RESPONDER group was significantly higher than the NON-RESPONDER\ngroup (36 vs. 30 ml/min/1.73 m2) (p < 0.001). Over time, the eGFR of the RESPONDER group stabilized or increased\n(p < 0.001). Over time, the eGFR in the NON-RESPONDER group decreased toward a trajectory of ESRD. Proteinuria\ndid not impact the response to 25-OH vitamin D replacement therapy. There were no identifiable variables\nassociated with the response or lack of response to cholecalciferol treatment.\nConclusions: CKD patients treated with cholecalciferol experience treatment resistance in raising vitamin D levels\nto a pre-selected target level. The mechanism of vitamin D resistance remains unknown and is associated with\nprogressive loss of eGFR. Proteinuria modifies but does not account for the vitamin D resistance.
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