Effect of Allopurinol on Markers of Mineral and Bone Metabolism

Effect of Allopurinol on Markers of Mineral and Bone Metabolism in Patients in With Chronic Kidney Disease: a Randomized Double-blind Study

Hyperuricemia is a common condition in patients with chronic kidney disease (CKD) in the glomerular filtration rate. Recently, it has been suggested that uric acid is related to a mineral and bone disease of CKD (CKD-MBD) since the high concentration of uric acid is associated with the harmful effect of vitamin D. The proof of concept of the association between acid uric acid and CKD-MBD is based on a prospective study (sample size 6) that observed, after 1 week of use of allopurinol, an increase in the concentration of 1,25(2D, a result independent of the concentration of calcium, phosphorus, 25(OH)D and PTH. An experimental study found that hyperuricemia could modify the expression of the 1α-hydroxylase enzyme, consequently reducing 1,25(OH). The current study aims to evaluate the action of allopurinol on CKD-MBD biomarkers (25(OH)-vitamin D, 1,25(OH)2D, FGF-23, PTH, calcium and phosphorus). We hypothesize that allopurinol can improve serum levels of 1,25(OH) 2D and PTH. This is a controlled, randomized, double-blind study, defined as a filtration rate < 60ml/1.73 m², according to the CKD-EPI equation. Inclusion criteria: patients with stages III, IV and V CKD who are not on dialysis with a serum level of 25(OH)-vitamin D >20 ng/ml. Exclusion criteria: Patients diagnosed with gout, undergoing treatment with allopurinol, patients already in use and drugs with sensitivity to the drug. Based on a previous study, we calculated a sample for 2 groups (placebo and drug) with pre and post-measurements (a total of 4). Considering a standard deviation of 4 and a difference of 7 in the treated group, 3 in the placebo group, and an alpha error of 5%, we calculated a sample of 25 patients in each arm.

In this randomized double-blind study, patients receive allopurinol or a placebo for 3 months. Dependent variables: 25(OH)-vitamin D, 1,25(OH)2D, FGF-23, PTH, calcium and phosphorus Population: stage 3, 4 or 5 CKD on conservative management at the Nephrology Service of Hospital das Clinicas HCFMUSP, Sao Paulo, Brazil. The same physician will follow patients. Adverse effects will be recorded.

pills exactly as the drug will be delivered to participants. Instructions will be made to take the pill once a day.

pills exactly as the placebo will be delivered to participants. Instructions will be made to take the pill once a day.

Inclusion Criteria: stage 3, 4 or 5 CKD on conservative management - Exclusion Criteria: allergy to allopurinol current treatment with allopurinol Gout