title: Weight Loss Mediated Reduction in Xanthine Oxidase Activity and Uric Acid Clearance in Adolescents with Severe Obesity.
abstract: Increased xanthine oxidase (XO) activity and uric acid levels are known to be associated with obesity and hypertension; however, it is not known if obesity is directly responsible for these associations in youth. This study investigated the effect of weight loss on XO activity, uric acid, and their relationship to blood pressure change in obese youth to provide greater insight on how obesity increases cardiovascular risk.
  
  
  
  This was an ancillary study in which 16 adolescents (mean age 15 ± 2 years) received meal replacement therapy over a period of four weeks. Outcomes measured at baseline and after intervention included weight, blood pressure, XO activity, plasma uric acid, uric acid clearance, and creatinine clearance.
  
  
  
  After the meal replacement intervention, participants experienced reductions in body weight (109.2 ± 16 kg vs. 105.2 ± 14 kg, p < 0.0001) and BMI (38.7 ± 4 kg vs. 37.4 ± 3 kg, p < 0.0001). Plasma XO activity was reduced by 9.8% (p = 0.016). Uric acid clearance was decreased by 39% (p = 0.006). SBP (systolic blood pressure) and plasma uric acid concentrations were reduced but did not achieve statistical significance (p = 0.34 and 0.38, respectively). DBP (diastolic blood pressure) was unchanged (p = 0.86). No significant relationships were found between changes in blood pressure and changes in either XO activity or plasma uric acid levels.
  
  
  
  Weight loss led to decreases in uric acid production by lowering XO activity and decreases in uric acid clearance by reducing glomerular filtration (GF) and increasing reabsorption. Changes in XO activity and uric acid levels did not correlate with changes in blood pressure.
authors.affiliation: 1 Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy , Minneapolis, MN.
authors.forename: Harrison K
authors.initials: HK
authors.lastname: Tam
authors.affiliation: 2 Department of Pediatrics, University of Minnesota Medical School , Minneapolis, MN.|3 Department of Medicine, University of Minnesota Medical School , Minneapolis, MN.
authors.forename: Aaron S
authors.initials: AS
authors.lastname: Kelly
authors.affiliation: 2 Department of Pediatrics, University of Minnesota Medical School , Minneapolis, MN.
authors.forename: Claudia K
authors.initials: CK
authors.lastname: Fox
authors.affiliation: 2 Department of Pediatrics, University of Minnesota Medical School , Minneapolis, MN.
authors.forename: Brandon M
authors.initials: BM
authors.lastname: Nathan
authors.affiliation: 1 Department of Experimental and Clinical Pharmacology, University of Minnesota College of Pharmacy , Minneapolis, MN.|2 Department of Pediatrics, University of Minnesota Medical School , Minneapolis, MN.
authors.forename: L'Aurelle A
authors.initials: LA
authors.lastname: Johnson
mesh_terms: D000293:Adolescent; D001794:Blood Pressure; D031204:Caloric Restriction; D005260:Female; D006801:Humans; D006973:Hypertension; D008297:Male; D008910:Minnesota / Q000453:epidemiology; D009767:Obesity, Morbid / Q000178:diet therapy* / Q000201:enzymology / Q000378:metabolism*; D063766:Pediatric Obesity / Q000178:diet therapy* / Q000201:enzymology / Q000378:metabolism*; D012307:Risk Factors; D014527:Uric Acid / Q000378:metabolism*; D015431:Weight Loss; D014969:Xanthine Oxidase / Q000378:metabolism*
chemical_list: D014527:Uric Acid; D014969:Xanthine Oxidase