title: ELISA analysis of urinary nephrin and podocalyxin standardized by aquaporin-2 in adult patients with nephrotic syndrome.
abstract: OBJECTIVE
  To investigate urinary nephrin and podocalyxin standardized by aquaporin (AQP)-2 using the enzyme-linked immunosorbent assay (ELISA) method in adult nephrotic syndrome (NS) patients.
  
  
  METHODS
  In 107 adult NS patients (27 proliferative nephritis, 77 non-proliferative, and 3 amyloidosis) undergoing renal biopsy, urinary nephrin, podocalyxin and AQP2 were measured by ELISA. Urinary nephrin and podocalyxin were standardized by AQP2 (neph/AQP and PCX/AQP) and values were compared with 11 healthy controls.
  
  
  RESULTS
  Urinary neph/AQP correlated positively to PCX/AQP (r = 0.51, p < 0.001). Urinary neph/AQP and PCX/AQP were lower in controls than NS patients. Both proliferative and non-proliferative NS patients excreted high urinary neph/AQP and PCX/AQP without a significant difference between them (p > 0.05). Patients with focal segmental glomerular sclerosis (FSGS) excreted higher urinary neph/AQP (p = 0.09) and PCX/AQP (p < 0.05) compared to the other patients. Urinary neph/AQP and PCX/AQP were increased in the immunoglobulin M nephropathy patients. Amyloidosis patients excreted lower neph/AQP and PCX/AQP. The sensitivity was 0.87 and specificity 0.37 when the neph/AQP borderline value of 0.16 was adopted [area under the curve (AUC) = 0.61]. The sensitivity was 0.74 and specificity 0.61 when the PCX/AQP borderline value was 3.06 (AUC = 0.69).
  
  
  CONCLUSIONS
  Urinary neph/AQP and PCX/AQP are increased in NS patients, with FSGS patients showing the highest levels. To distinguish FSGS from other NS forms, the measurement of urinary PCX/AQP may be a practical method, and superior to neph/AQP.
authors.affiliation: Department of Nephrology, Hangzhou Hospital of Traditional Chinese Medicine (Guangxing Hospital), Zhejiang Chinese Medical University, Hangzhou, Zhejiang Province, China, zhubing@hotmail.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhu
authors.forename: Xian-fa
authors.initials: XF
authors.lastname: Li
authors.forename: Xiao-ling
authors.initials: XL
authors.lastname: Zhu
authors.forename: Yi
authors.initials: Y
authors.lastname: Lin
authors.forename: Sen
authors.initials: S
authors.lastname: Zhong
authors.forename: Cai-feng
authors.initials: CF
authors.lastname: Zhu
authors.forename: Xuan-li
authors.initials: XL
authors.lastname: Tang
authors.forename: Yun-qing
authors.initials: YQ
authors.lastname: Hu
authors.forename: Xiao-xia
authors.initials: XX
authors.lastname: Cheng
authors.forename: Yong-jun
authors.initials: YJ
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000686:Amyloidosis / Q000652:urine*; D051399:Aquaporin 2 / Q000652:urine*; D016022:Case-Control Studies; D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005921:Glomerulonephritis / Q000652:urine*; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000652:urine*; D008875:Middle Aged; D009402:Nephrosis, Lipoid / Q000652:urine; D009404:Nephrotic Syndrome / Q000473:pathology / Q000652:urine*; D050199:Podocytes; D012680:Sensitivity and Specificity; D012795:Sialoglycoproteins / Q000652:urine*; D014556:Urine / Q000166:cytology; D055815:Young Adult
chemical_list: D051399:Aquaporin 2; D008565:Membrane Proteins; D012795:Sialoglycoproteins; C113267:nephrin; C001643:podocalyxin
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