title: Comparison of symmetric dimethylarginine with creatinine, cystatin C and their eGFR equations as markers of kidney function.
abstract: OBJECTIVE
  Symmetric dimethylarginine (SDMA) is a catabolic product of arginine-methylated proteins and is an emerging biomarker for kidney function. A limited number of studies in selected populations have shown good correlation between SDMA and a few known markers of glomerular filtration rate (GFR). However, a comprehensive comparison of SDMA with all existing serum endogenous markers in a population with varied kidney function and against measured GFR is lacking. The objective of this study was to compare the correlations of SDMA, creatinine, cystatin C and their eGFR equations against GFR measured by iothalamate clearance in an adult population with varied kidney function.
  
  
  METHODS
  Left-over serum and plasma specimens were collected from 40 adults with normal and reduced kidney function. GFR was measured using a radioactive iothalamate procedure. Creatinine and cystatin C were measured on Roche Cobas 8000. SDMA was measured by a published liquid chromatography-tandem mass spectrometry method.
  
  
  RESULTS
  SDMA correlated highly with measured GFR (r=-0.84), which was better than creatinine (r=-0.70) but equivalent to cystatin C (r=-0.86) and the eGFR equations [MDRD and CKD-EPI (separate and combined)].
  
  
  CONCLUSIONS
  SDMA is a strong marker of kidney function and further studies are needed to establish an eGFR formula that includes it for widespread clinical use.
authors.affiliation: Department of Laboratory Medicine, Yale University, New Haven, CT 06510, United States.
authors.forename: Joe M
authors.initials: JM
authors.lastname: El-Khoury
authors.affiliation: Department of Laboratory Medicine, Cleveland Clinic, Cleveland, OH 44195, United States.
authors.forename: Dustin R
authors.initials: DR
authors.lastname: Bunch
authors.affiliation: Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH 44195, United States.
authors.forename: Bo
authors.initials: B
authors.lastname: Hu
authors.affiliation: Department of Laboratory Medicine, Cleveland Clinic, Cleveland, OH 44195, United States.
authors.forename: Drew
authors.initials: D
authors.lastname: Payto
authors.affiliation: Department of Laboratory Medicine, Cleveland Clinic, Cleveland, OH 44195, United States.
authors.forename: Edmunds Z
authors.initials: EZ
authors.lastname: Reineks
authors.affiliation: Department of Laboratory Medicine, Cleveland Clinic, Cleveland, OH 44195, United States. Electronic address: wangs2@ccf.org.
authors.forename: Sihe
authors.initials: S
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D001120:Arginine / Q000031:analogs & derivatives* / Q000097:blood; D015415:Biomarkers / Q000097:blood*; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007677:Kidney Function Tests / Q000379:methods*; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D015415:Biomarkers; D055316:Cystatin C; C024917:symmetric dimethylarginine; D001120:Arginine; D003404:Creatinine
keywords: Cystatin c; Glomerular filtration rate; Kidney function; Symmetric dimethylarginine; eGFR