ASSOCIATIONS BETWEEN SERUM-INTACT PARATHYROID HORMONE, SERUM 25-HYDROXYVITAMIN D, ORAL VITAMIN D ANALOGS AND METABOLIC SYNDROME IN PERITONEAL DIALYSIS PATIENTS: A MULTI-CENTER CROSS-SECTIONAL STUDY

Introduction: Although previous studies have suggested associations between serum intact parathyroid hormone (iPTH), 25-hydroxyvitamin D (25(OH) D) and metabolic syndrome (MS) in the general population, these associations are still uncharacterized in peritoneal dialysis (PD) patients. Methods: In total, 837 prevalent PD patients from 5 centers in China were enrolled between April 1, 2011 and November 1, 2011. The demographic data, biochemical parameters and medical records were collected, except for serum 25(OH) D which was measured in 347 of 837 patients. The definition of MS was modified from National Cholesterol Education Program Third Adult Treatment Panel (NCEP-ATPIII). Results: 55.4% of 837 patients were found to have MS. The median concentration of iPTH, 25(OH) D and doses of oral vitamin D analogs for participants with MS was significantly lower than those without MS. The iPTH, 25(OH) D values and doses of vitamin D analogs were all associated with one or more components of MS. After multivariate adjustment, low serum iPTH values and oral vitamin D analogs, rather than serum 25(OH) D, were significantly associated with the presence of MS, abnormal fasting blood glucose (FBG) and high-density lipoprotein cholesterol (HDL-C). Compared to iPTH < 130pg/mL, iPTH 130-585 pg/mL and > 585pg/mL were associated with a lower risk of MS with adjusted odds ratio (OR) of 0.59 and 0.33, respectively. Taking vitamin D analogs was also associated with a lower risk of MS with adjusted OR of 0.55. Conclusions: Serum iPTH and the use of active vitamin D supplements rather than serum 25(OH) D were independently associated with the presence of MS in patients on PD.