title: Reduced serum fetuin-A in nephrotic children: a consequence of proteinuria?
abstract: BACKGROUND
  The extracellular protein fetuin-A is a potent soluble inhibitor of calcification, and its deficiency has been associated with vascular calcification in dialysis patients. In proteinuric patients, significant urinary losses of fetuin-A may cause low serum fetuin-A levels.
  
  
  METHODS
  In a cross-sectional study, urinary/serum concentrations of fetuin-A were investigated in proteinuric children with glomerular diseases and preserved renal function (n = 58) in comparison to healthy controls (n = 246).
  
  
  RESULTS
  Mean fetuin-A serum concentrations were clearly reduced in children with nephrotic syndrome (0.25 ± 0.14 g/l, p < 0.001), slightly reduced in children with large proteinuria (0.39 ± 0.15 g/l, p < 0.05), and comparable to controls in those with mild proteinuria (0.45 ± 0.14 vs. 0.46 ± 0.12 g/l). Fetuin-A was positively correlated with serum protein (r = 0.58), albumin (r = 0.57), and calcium (r = 0.64), but negatively correlated with proteinuria (r = -0.41), albuminuria (r = -0.46), and urinary fetuin-A excretion (r = -0.48; each p < 0.001). The fractional excretion of fetuin-A was significantly associated with the degree of proteinuria and serum fetuin-A levels. However, the urinary loss of fetuin-A and albumin in nephrotic children differed by three orders of magnitude and the mean fractional excretion of fetuin-A was only 1/10 of that of albumin (0.016 ± 0.029 vs. 0.162 ± 0.403%; p < 0.001).
  
  
  CONCLUSIONS
  Fetuin-A is clearly reduced in children with nephrotic syndrome and associated with the degree of hypoalbuminemia. This is due to urinary fetuin-A loss and/or reduced hepatic synthesis. Persistent fetuin-A deficiency may have an impact on cardiovascular morbidity in nephrotic children.
authors: Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Carl-Neuberg-Strasse 1, Hannover, Germany. fischer.dagmar-christiane@mh-hannover.de
authors: Dagmar-Christiane
authors: DC
authors: Fischer
authors: Jan
authors: J
authors: Schaible
authors: Marianne
authors: M
authors: Wigger
authors: Hagen
authors: H
authors: Staude
authors: Erdmute
authors: E
authors: Drueckler
authors: Guenther
authors: G
authors: Kundt
authors: Dieter
authors: D
authors: Haffner
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D034141:Hypoalbuminemia; D007223:Infant; D007231:Infant, Newborn; D007674:Kidney Diseases / Q000097:blood* / Q000652:urine*; D007678:Kidney Glomerulus / Q000473:pathology; D008297:Male; D009401:Nephrosis; D009404:Nephrotic Syndrome / Q000097:blood / Q000652:urine; D011507:Proteinuria / Q000097:blood* / Q000652:urine; D060749:alpha-2-HS-Glycoprotein / Q000096:biosynthesis* / Q000652:urine*
chemical_list: D060749:alpha-2-HS-Glycoprotein