title: Fractional excretion of uric acid as a predictor for saline responsiveness in long-term kidney transplant patients.
abstract: OBJECTIVE
  Subclinical hypovolemia may contribute to allograft dysfunction in long-term kidney transplant (KT) patients. In order to predict responsiveness to saline hydration, indices for tubular transport were investigated.
  
  
  METHODS
  Fifty-four clinically euvolemic long-term KT patients with recently aggravated azotemia were given intravenous hydration as follows: 0.9% saline 5 ml/kg over 1 h, followed by 0.9% saline 1 ml/kg/h over 12 h and 1 liter of 0.45% saline over the next 24 h. Serum and urine data were collected and analyzed to assess responses.
  
  
  RESULTS
  In all patients, saline hydration relieved azotemia, as shown by blood urea nitrogen (46.9 ± 17.2 vs. 39.3 ± 15.4 mg/dl; p < 0.01) and serum creatinine levels (2.9 ± 1.1 vs. 2.5 ± 1.1 mg/dl; p < 0.01) on day 0 versus day 2. In 38 patients, serum creatinine did not increase in the following month (70% responders). Compared with the nonresponders, the responders had a higher urine-to-plasma creatinine ratio and lower fractional excretion of sodium, uric acid and urea at admission. Multivariate logistic regression analysis revealed that responsiveness to saline hydration was independently associated with lower fractional excretion of uric acid.
  
  
  CONCLUSIONS
  Subclinical hypovolemia should be considered in long-term KT patients with azotemia of unexplainable causes. Fractional excretion of uric acid may predict responsiveness to saline hydration.
authors.affiliation: Department of Internal Medicine, Hanyang University College of Medicine, Seoul, South Korea.
authors.forename: Jong-Wook
authors.initials: JW
authors.lastname: Choi
authors.forename: Joon-Sung
authors.initials: JS
authors.lastname: Park
authors.forename: Tai Yeon
authors.initials: TY
authors.lastname: Koo
authors.forename: Chang Hwa
authors.initials: CH
authors.lastname: Lee
authors.forename: Chong Myung
authors.initials: CM
authors.lastname: Kang
authors.forename: Gheun-Ho
authors.initials: GH
authors.lastname: Kim
mesh_terms: D000328:Adult; D053099:Azotemia / Q000175:diagnosis / Q000453:epidemiology / Q000652:urine*; D015415:Biomarkers / Q000652:urine; D005260:Female; D006801:Humans; D020896:Hypovolemia / Q000175:diagnosis / Q000453:epidemiology / Q000652:urine*; D016030:Kidney Transplantation / Q000009:adverse effects / Q000639:trends*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012965:Sodium Chloride / Q000008:administration & dosage*; D013997:Time Factors; D014527:Uric Acid / Q000652:urine*
chemical_list: D015415:Biomarkers; D014527:Uric Acid; D012965:Sodium Chloride