title: Can we compare serum sclerostin results obtained with different assays in hemodialysis patients?
abstract: OBJECTIVE
  Sclerostin, secreted by osteocytes, plays a key role in antagonizing bone formation. Recent studies, which seldom include chronic kidney disease (CKD) patients, have reported on the association of sclerostin and mortality, with contradictory results. The assay-linked variability may contribute to these discrepant results.
  
  
  METHODS
  We have compared sclerostin results obtained with two assays (TECO and Biomedica) in a cohort of 91 CKD patients undergoing hemodialysis.
  
  
  RESULTS
  We found a strong correlation (r = 0.870, p < 0.0001) between the serum sclerostin concentrations measured by the two assays. Bland-Altman plot shows that, although there was a partial agreement between the assays, differences found for individual values (-0.27 ± 0.54; ranging from -1.3 to 0.8 ng/ml) were quite unpredictable. By using TECO, there was a significant relationship between serum sclerostin, and calcitonin (r = 0.224), IL-6 (r = 0.251) and FGF23 (r = 0.331) levels while no correlation was found with PTH or total alkaline phosphatase. Regarding Biomedica, there was a significant correlation with calcitonin (r = 0.260), and β2 microglobulin (r = 0.210), but no correlation with PTH or total alkaline phosphatase. Overall, 25.3% among the patients had different classifications as to normal or high values, according to the manufacturer.
  
  
  CONCLUSIONS
  Sclerostin levels should be interpreted with caution, as they can vary widely according to the assay used. Further studies are clearly needed before considering sclerostin as a true marker of mortality. Moreover, we do not know at present which serum sclerostin levels should be regarded as either normal or potentially dangerous in patients with CKD.
authors: Universidade Nove de Julho (UNINOVE), Rua Iperoig, 690 ap 121 - Perdizes, São Paulo, SP, 050016-000, Brazil, rosa.moyses@uol.com.br.
authors: Rosa M A
authors: RM
authors: Moysés
authors: Sophie A
authors: SA
authors: Jamal
authors: Fabiana G
authors: FG
authors: Graciolli
authors: Luciene M
authors: LM
authors: dos Reis
authors: Rosilene M
authors: RM
authors: Elias
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D001851:Bone Diseases, Metabolic / Q000097:blood* / Q000209:etiology; D019485:Bone Morphogenetic Proteins / Q000097:blood*; D002116:Calcitonin / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood; D005819:Genetic Markers; D006801:Humans; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D006435:Renal Dialysis; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000150:complications / Q000628:therapy; D055815:Young Adult; D001613:beta 2-Microglobulin / Q000097:blood
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D019485:Bone Morphogenetic Proteins; C000717427:FGF23 protein, human; D005819:Genetic Markers; D015850:Interleukin-6; D010281:Parathyroid Hormone; C422903:SOST protein, human; D001613:beta 2-Microglobulin; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D002116:Calcitonin; D000469:Alkaline Phosphatase