title: Comparison of 24-h urinary aldosterone level and random urinary aldosterone-to-creatinine ratio in the diagnosis of primary aldosteronism.
abstract: BACKGROUND
  Historically, urinary aldosterone level measurement was a commonly employed confirmatory test to detect primary aldosteronism (PA). However, 24-h urine collection is inconvenient and cumbersome. We hypothesized that random urinary aldosterone measurements with correction for creatinine concentration might be comparable to 24-h urinary aldosterone levels (Uald-24 h) in the diagnosis of PA.
  
  
  METHODS
  The non-concurrent prospective study was conducted between June 2006 and March 2008 in patients admitted for confirmation of aldosteronism by salt loading test. A 24-h urine sample, which was collected during hospitalization on the day before saline infusion testing after restoration of serum hypokalemia, was collected from all subjects. Moreover, participants were asked to collect a first bladder voiding random urine sample during clinic visits. Uald-24 h and the random urinary aldosterone-to-creatinine ratio (UACR) were calculated accordingly.
  
  
  RESULTS
  A total of 102 PA patients (71 patients diagnosed of aldosterone-producing adenoma, 31 with idiopathic hyperaldosteronism) and 65 patients with EH were enrolled. The receiver operating characteristic curve showed comparable areas under the curves of UACR and Uald-24 h. The Bland-Altman plot showed mean bias but no obvious heteroscedasticity between the two tests. When using random UACR >3.0 ng/mg creatinine as the cutoff value, we obtained a specificity of 90.6% to confirm PA from essential hypertension.
  
  
  CONCLUSIONS
  Our study reinforce that the diagnostic accuracy of random UACR was comparable to that of Uald-24 h in PA patients. With the quickness and simplicity of the UACR method and its equivalence to Uald-24 h, this assay could be a good alternative diagnostic tool for PA confirmation.
authors.affiliation: Division of Nephrology, Buddhist Tzu Chi General Hospital, Taipei Branch, Taiwan.
authors.forename: Che-Hsiung
authors.initials: CH
authors.lastname: Wu
authors.forename: Ya-Wen
authors.initials: YW
authors.lastname: Yang
authors.forename: Ya-Hui
authors.initials: YH
authors.lastname: Hu
authors.forename: Yao-Chou
authors.initials: YC
authors.lastname: Tsai
authors.forename: Ko-Lin
authors.initials: KL
authors.lastname: Kuo
authors.forename: Yen-Hung
authors.initials: YH
authors.lastname: Lin
authors.forename: Szu-Chun
authors.initials: SC
authors.lastname: Hung
authors.forename: Vin-Cent
authors.initials: VC
authors.lastname: Wu
authors.forename: Kwan-Dun
authors.initials: KD
authors.lastname: Wu
mesh_terms: D000236:Adenoma / Q000150:complications / Q000652:urine*; D000310:Adrenal Gland Neoplasms / Q000150:complications / Q000652:urine*; D000328:Adult; D000450:Aldosterone / Q000652:urine*; D003404:Creatinine / Q000652:urine*; D000075222:Essential Hypertension; D005260:Female; D006801:Humans; D006929:Hyperaldosteronism / Q000175:diagnosis* / Q000209:etiology / Q000652:urine*; D006973:Hypertension / Q000652:urine; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve
chemical_list: D000450:Aldosterone; D003404:Creatinine