title: Association between ambient carbon monoxide and secondary hyperparathyroidism in nondiabetic patients undergoing peritoneal dialysis.
abstract: BACKGROUND
  Secondary hyperparathyroidism (SHPT) is a major disorder in patients with chronic renal disease with or without dialysis. Air pollution has been confirmed as being associated with increased incidence of human morbidity and mortality. To our knowledge, investigating air pollution as a dialysis-unrelated factor for SHPT in patients undergoing dialysis is limited. We developed this study to assess the effect of air pollution and other important risk factors on SHPT in patients undergoing peritoneal dialysis (PD).
  
  
  METHODS
  We recruited a total of 141 patients who did not have diabetes mellitus, were nonsmokers, and were undergoing PD in this cross-sectional study. We analyzed the difference in air quality based on the patients' living areas. We estimated demographic, hematological, nutritional, inflammatory, biochemical, air pollutant, and dialysis-related data based on this cross-sectional study. Subgroup analysis of the relationship between air pollutants and the clinical variables and having or not having hyperparathyroidism (HPT) (intact parathyroid hormone level ≥180 pg/dL) was also performed.
  
  
  RESULTS
  A total of 141 patients undergoing PD (30 men and 111 women) were enrolled in the study. Sixty-eight patients had SHPT. In a binary logistic regression, high environmental CO exposure (odds ratio [OR] 3.22, 95% confidence interval [CI] 1.42-7.28; P=0.005), serum phosphate levels (OR 1.66, 95% CI 1.17-2.37; P=0.005), hypoalbuminemia (OR 3.76, 95% CI 1.29-10.94; P=0.015), and use of calcitriol (OR 8.25, 95% CI 3.43-19.85; P<0.001) were positively associated with SHPT.
  
  
  CONCLUSIONS
  The findings of this cross-sectional study indicated the presence of an association between environmental CO exposure and SHPT in patients undergoing PD who did not have diabetes mellitus. Therefore, poor environmental air quality may be a risk factor for deterioration of SHPT in patients undergoing PD.
authors.affiliation: Department of Nephrology, Division of Clinical Toxicology, Chang Gung Memorial Hospital, Linkou, Taiwan ; College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Cheng-Hao
authors.initials: CH
authors.lastname: Weng
authors.affiliation: Liver Research Unit, Department of Hepatogastroenterology, Chang Gung Memorial Hospital, Keelung, Taiwan.
authors.forename: Ching-Chih
authors.initials: CC
authors.lastname: Hu
authors.affiliation: Department of Nephrology, Division of Clinical Toxicology, Chang Gung Memorial Hospital, Linkou, Taiwan ; College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Tzung-Hai
authors.initials: TH
authors.lastname: Yen
authors.affiliation: Department of Nephrology, Division of Clinical Toxicology, Chang Gung Memorial Hospital, Linkou, Taiwan ; College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Wen-Hung
authors.initials: WH
authors.lastname: Huang
keywords: CO; air pollution; carbon monoxide; hyperparathyroidism; peritoneal dialysis