title: Creatinine or cystatin C - which is a better index of renal function in morbid obesity?
abstract: OBJECTIVE
  The most important index of renal function is estimated glomerular filtration rate (eGFR) which can be calculated from creatinine or cystatin C concentration in serum. There is uncertainty, which formula is best suited to assess renal function in morbidly obese patients. The aim of this study was to evaluate eGFR in patients with morbid obesity using formulas: Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Grubb, Le Bricon, Hoek, Larsson, and to compare the obtained results.
  
  
  METHODS
  In 40 morbidly obese patients, serum concentration of cystatin C and creatinine were assayed. Values of eGFR were calculated using the above-mentioned formulas.
  
  
  RESULTS
  The mean value of eGFR ranged from 85.9 to 111.1 ml/min/1.73 m², depending on the formula. The biggest difference between the obtained values was 29% (Grubb vs. Hoek p<0.01). After calculation of eGFR from creatinine concentration (MDRD), 7 patients were qualified to the 2nd and 3rd stage of chronic renal disease, while application of Hoek's formula, based on cystatin C concentration, allotted 27 patients to 2nd and 3rd stage of chronic renal disease. Le Bricon formula gave eGFR values, that correlated best with albuminuria.
  
  
  CONCLUSIONS
  eGFR calculated using Le Bricon formula based on the cystatin C concentration was significantly lower than eGFR calculated from creatinine concentration and was more closely associated with albuminuria. Relying only on creatinine concentration to estimate glomerular filtration rate can lead to underestimation of renal malfunction in obese patients.
authors.forename: P
authors.initials: P
authors.lastname: Mysliwiec
authors.forename: P
authors.initials: P
authors.lastname: Jasiewicz
authors.forename: H R
authors.initials: HR
authors.lastname: Hady
authors.forename: B
authors.initials: B
authors.lastname: Choromanska
authors.forename: B
authors.initials: B
authors.lastname: Mroczko
authors.forename: H
authors.initials: H
authors.lastname: Mysliwiec
authors.forename: A
authors.initials: A
authors.lastname: Siemiatkowski
authors.forename: J
authors.initials: J
authors.lastname: Dadan
authors.forename: M
authors.initials: M
authors.lastname: Szmitkowski
mesh_terms: D000328:Adult; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D015994:Incidence; D007677:Kidney Function Tests / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009767:Obesity, Morbid / Q000453:epidemiology / Q000378:metabolism*; D051436:Renal Insufficiency, Chronic / Q000453:epidemiology / Q000378:metabolism*; D012307:Risk Factors
chemical_list: C525030:CST3 protein, human; D055316:Cystatin C; D003404:Creatinine