title: Uric acid biorhythm, a feature of long-term variation in a clinical laboratory database.
abstract: BACKGROUND
  The biorhythm of serum uric acid was evaluated in a large sample of a clinical laboratory database by spectral analysis and the influence of the gender and age on uric acid variability.
  
  
  METHODS
  Serum uric acid values were extracted from a large database of a clinical laboratory from May 2000 to August 2006. Outlier values were excluded from the analysis and the remaining data (n=73,925) were grouped by gender and age ranges. Rhythm components were obtained by the Lomb Scargle method and Cosinor analysis.
  
  
  RESULTS
  Serum uric acid was higher in men than in women older than 13 years (p<0.05). Compared with 0-12 year group, uric acid increased in men but not in women older than 13 years (p<0.05). Circannual (12 months) and transyear (17 months) rhythm components were detected, but they were significant only in adult individuals (>26 years, p<0.05). Cosinor analysis showed that midline estimating statistic of rhythm (MESOR) values were higher in men (range: 353-368 μmol/L) than in women (range: 240-278 μmol/L; p<0.05), independent of the age and rhythm component. The extent of predictable change within a cycle, approximated by the double amplitude, represented up to 20% of the corresponding MESOR.
  
  
  CONCLUSIONS
  Serum uric acid biorhythm is dependent on gender and age and it may have relevant influence on preanalytical variability of clinical laboratory results.
authors.affiliation: Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Pacheco de Andrade
authors.forename: Rosario D C
authors.initials: RD
authors.lastname: Hirata
authors.forename: Fabiano
authors.initials: F
authors.lastname: Sandrini
authors.forename: Alvaro
authors.initials: A
authors.lastname: Largura
authors.forename: Mario Hiroyuki
authors.initials: MH
authors.lastname: Hirata
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D016208:Databases, Factual; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010507:Periodicity; D012737:Sex Factors; D014527:Uric Acid / Q000097:blood*; D055815:Young Adult
chemical_list: D014527:Uric Acid