title: Hyperuricaemia is associated with renal damage independently of hypertension and intrarenal renin-angiotensin system activation, as well as their circadian rhythms.
abstract: OBJECTIVE
  Both hyperuricaemia and activation of the intrarenal renin-angiotensin system (RAS) play an important role in the development of hypertension and renal damage. However, it has not been clear whether hyperuricaemia is associated with renal damage due to hypertension or intrarenal RAS activation, as well as their circadian rhythms.
  
  
  METHODS
  We recruited 43 chronic kidney disease (CKD) patients who did not receive RAS blockers and antihyperuricaemic drugs, and investigated the relationship among serum uric acid (sUA) levels, the circadian rhythm of urinary angiotensinogen (U-AGT) excretion levels, and the levels of albuminuria (U-ACR) and proteinuria (U-P/Cr).
  
  
  RESULTS
  sUA levels were significantly associated with estimated glomerular filtration rate (eGFR) (P = 0.002), systolic blood pressure (SBP) (daytime, P = 0.031), and U-ACR (daytime, P = 0.006 and nighttime, P = 0.008) and U-P/Cr (daytime, P = 0.017 and nighttime, P = 0.013). However, there were no significant differences between sUA levels and SBP in nighttime and U-AGT excretion levels in both time periods. Multiple regression analyses for sUA levels were performed using age, sex, eGFR and each parameter (SBP, U-AGT/Cr, U-ACR or U-P/Cr). sUA levels were not associated with SBP or U-AGT/Cr in both time periods. sUA levels tended to correlate with U-P/Cr levels in nighttime, and were significantly associated with U-P/Cr in daytime (P = 0.026) and U-ACR in daytime (P = 0.017) and nighttime (P = 0.046). Moreover, no significant differences were found between sUA levels and night-to-day ratios of some parameters.
  
  
  CONCLUSIONS
  These data suggest that hyperuricaemia is associated with renal damage, independently of hypertension and intrarenal RAS activation, as well as their circadian rhythms.
authors.affiliation: Internal Medicine 1, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Naro
authors.initials: N
authors.lastname: Ohashi
authors.affiliation: Internal Medicine 1, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Ishigaki
authors.affiliation: Internal Medicine 1, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Isobe
authors.affiliation: Internal Medicine 1, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Tsuji
authors.affiliation: Internal Medicine 1, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Takamasa
authors.initials: T
authors.lastname: Iwakura
authors.affiliation: Internal Medicine 1, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Ono
authors.affiliation: Internal Medicine 1, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Tsuji
authors.affiliation: Blood Purification Unit, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Yukitoshi
authors.initials: Y
authors.lastname: Sakao
authors.affiliation: Blood Purification Unit, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kato
authors.affiliation: Internal Medicine 1, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Yasuda
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000419:Albuminuria / Q000209:etiology; D000808:Angiotensinogen / Q000652:urine; D015415:Biomarkers / Q000097:blood / Q000652:urine; D001794:Blood Pressure; D002940:Circadian Rhythm; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology; D033461:Hyperuricemia / Q000097:blood / Q000150:complications* / Q000175:diagnosis; D007668:Kidney / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D007674:Kidney Diseases / Q000175:diagnosis / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012084:Renin-Angiotensin System; D012307:Risk Factors; D013997:Time Factors; D014527:Uric Acid / Q000097:blood; D055815:Young Adult
chemical_list: D015415:Biomarkers; D000808:Angiotensinogen; D014527:Uric Acid
keywords: circadian rhythm; hypertension; intrarenal renin-angiotensin system; renal damage; uric acid