title: Elucidation of the etiology and characteristics of pink urine in young healthy subjects.
abstract: BACKGROUND
  Pink urine syndrome (PUS) is attributed to the precipitation of uric acid caused by low urinary pH (U-pH). However, the reasons for the lower U-pH are unclear.
  
  
  OBJECTIVE
  To investigate the occurrence of PUS and verified the cause of U-pH reduction.
  
  
  METHODS
  Participants comprised 4,940 students who had undergone a physical examination. Data on the presence [PUS (+)] or absence [PUS (-)] of PUS, as well as age, gender, body mass index (BMI), blood pressure (BP), heart rate (HR), and U-pH were collected. Of these participants, 300 randomly selected individuals were evaluated for their waist circumference, as well as their levels of urinary C-peptide, angiotensinogen, methylglyoxal, thiobarbituric acid-reactive substances (TBARS), and Na(+) excretion. Independent risk factors of lower U-pH were decided by a multiple-regression analysis.
  
  
  RESULTS
  PUS was observed in 216 students (4.4 %). A greater number of men comprised the PUS (+) group compared with the PUS (-) group, and subjects in this group had high BMI, BP, and HR values, as well as low U-pH. A logistic regression analysis revealed that the BMI and U-pH were independent risk factors for PUS (+). The decrease of U-pH was closely related to the progress of chronic kidney disease (CKD). BMI value was related to PUS (+) in the CKD (-) subjects. On the other hand, low U-pH was related to PUS (+) in the CKD (+) subjects. All factors other than HR showed a significant negative correlation with U-pH. However, multiple-regression analysis revealed that TBARS and angiotensinogen were independent risk factors.
  
  
  CONCLUSIONS
  Obesity and lower U-pH were each independently related to PUS, whereas increased intrarenal oxidative stress and exacerbation of the renin-angiotensin system activation were associated with the lowering of U-pH. U-pH low value is related to potential CKD.
authors.affiliation: Division of Nephrology, Endocrinology and Vascular Medicine, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, 980-8574, Japan. ogawa-s@hosp.tohoku.ac.jp.|Section of Clinical Medicine, Division of Research in Student Support, Institute for Excellence in Higher Education, Tohoku University, Sendai, Japan. ogawa-s@hosp.tohoku.ac.jp.
authors.forename: Susumu
authors.initials: S
authors.lastname: Ogawa
authors.affiliation: Section of Clinical Medicine, Division of Research in Student Support, Institute for Excellence in Higher Education, Tohoku University, Sendai, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Takiguchi
authors.affiliation: Division of Nephrology, Endocrinology and Vascular Medicine, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, 980-8574, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nako
authors.affiliation: Division of Nephrology, Endocrinology and Vascular Medicine, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, 980-8574, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Okamura
authors.affiliation: Division of Nephrology, Endocrinology and Vascular Medicine, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, 980-8574, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Trim Medical Institute Co., Ltd., Osaka, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kabayama
authors.affiliation: Division of Nephrology, Endocrinology and Vascular Medicine, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, 980-8574, Japan.
authors.forename: Takefumi
authors.initials: T
authors.lastname: Mori
authors.affiliation: Section of Clinical Medicine, Division of Research in Student Support, Institute for Excellence in Higher Education, Tohoku University, Sendai, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Kinouchi
authors.affiliation: Division of Nephrology, Endocrinology and Vascular Medicine, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, 980-8574, Japan.
authors.forename: Sadayoshi
authors.initials: S
authors.lastname: Ito
mesh_terms: D000293:Adolescent; D000808:Angiotensinogen / Q000652:urine; D044466:Asian People; D001794:Blood Pressure; D015992:Body Mass Index; D003116:Color; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D009765:Obesity / Q000150:complications / Q000652:urine; D011765:Pyruvaldehyde / Q000652:urine; D012307:Risk Factors; D013577:Syndrome; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014527:Uric Acid / Q000652:urine*; D014570:Urologic Diseases / Q000453:epidemiology / Q000378:metabolism / Q000652:urine*; D055105:Waist Circumference; D055815:Young Adult
chemical_list: D017392:Thiobarbituric Acid Reactive Substances; D000808:Angiotensinogen; D014527:Uric Acid; D011765:Pyruvaldehyde
keywords: Angiotensinogen; Methylglyoxal; Oxidative stress; Pink urine syndrome; Urinary pH