title: Associations of plasma uric acid and purine metabolites with blood pressure in children: the KOALA Birth Cohort Study.
abstract: Elevated serum uric acid concentration has been associated with high blood pressure (BP) and hypertension. A putative underlying mechanism is the accumulation of reactive oxygen species when uric acid is generated by an increased enzyme activity of xanthine oxidase (XO). The aims of the present study were to investigate the associations between plasma uric acid concentration, purine metabolite ratios, as proxies for increased XO activity, and SBP and DBP in school-age children.
  
  
  
  Cross-sectional analyses were performed in 246 children (46% boys; mean age 7.1 years) from the Dutch KOALA Birth Cohort Study. Purine metabolites were determined with ultra-performance liquid chromatography-tandem mass spectrometry. During a home visit, a nurse collected a blood sample and measured BP three times; in addition, parents measured their child's BP on three consecutive days, in the morning and evening. Generalized estimating equations were used for analyses while controlling for variables such as sex, age, BMI, physical activity, and dietary intake.
  
  
  
  In multivariable analysis, uric acid (per SD of 38 μmol/l) was associated with DBP z-scores [sβ 0.07; confidence interval (CI), 0.01-1.14], but not with SBP z-scores. Higher ratios of uric acid/xanthine (per SD of 138) (sβ 0.09; CI, 0.01-0.17) and xanthine/hypoxanthine (per SD of 321) (sβ 0.08; CI, 0.02-0.17) were associated with higher DBP z-scores, but not with SBP z-scores.
  
  
  
  In school-age children, uric acid and the ratios of uric acid/xanthine and xanthine/hypoxanthine were significantly associated with DBP z-scores. Suggesting that, both uric acid concentration and increased XO activity are associated with BP.
authors.affiliation: aDivision of Rheumatology, Department of Internal Medicine, Maastricht University Medical CentrebCAPHRI School for Public Health and Primary CarecDepartment of Epidemiology, Maastricht UniversitydDepartment of Clinical Genetics, Maastricht University Medical Centre, Maastricht, The NetherlandseResearch Unit Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Diseases, Studies Coordinating Centre, University of Leuven, Leuven, BelgiumfDepartment of Internal Medicine, Maasticht University Medical CentergCARIM School for Cardiovascular Diseases, Maastricht University Medical CentrehCARIM School for Cardiovascular Diseases, and MaCSBio Maastricht Centre for Systems Biology, Maastricht University, Maastricht, The Netherlands.
authors.forename: Lieke E J M
authors.initials: LE
authors.lastname: Scheepers
authors.forename: Annelies
authors.initials: A
authors.lastname: Boonen
authors.forename: Wieke
authors.initials: W
authors.lastname: Pijnenburg
authors.forename: Jörgen
authors.initials: J
authors.lastname: Bierau
authors.forename: Jan A
authors.initials: JA
authors.lastname: Staessen
authors.forename: Coen D A
authors.initials: CD
authors.lastname: Stehouwer
authors.forename: Carel
authors.initials: C
authors.lastname: Thijs
authors.forename: Ilja C W
authors.initials: IC
authors.lastname: Arts
mesh_terms: D001794:Blood Pressure; D002648:Child; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003971:Diastole; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000201:enzymology; D019271:Hypoxanthine / Q000097:blood*; D008297:Male; D011687:Purines / Q000378:metabolism; D013599:Systole; D014527:Uric Acid / Q000097:blood*; D019820:Xanthine / Q000097:blood*; D014969:Xanthine Oxidase / Q000378:metabolism*
chemical_list: D011687:Purines; D019820:Xanthine; D014527:Uric Acid; D019271:Hypoxanthine; D014969:Xanthine Oxidase; C030985:purine