title: [Estimation of glomerular filtration rate using weight/creatinine formula].
abstract: OBJECTIVE
  The correct management of patients with chronic renal disease depends on an early diagnosis. The aim of this study was to evaluate the usefulness, in the daily clinical practice, of the weight/creatinine formula as an indirect measurement of glomerular filtration.
  
  
  METHODS
  1,025 ambulatory patients were referred to the Nephrology Laboratory for basic blood and urine analysis. Creatinine clearance was calculated with the standard formula.
  
  
  RESULTS
  A good correlation between the creatinine clearance adjusted for the corporal surface and that estimated by the weight/creatinine formula was observed, especially when creatinine levels were between 1.5-3 mg/dl and patients were older than 60 years. The mean difference between both methods was 6.3 (14.5) ml/min for males and 2.4 (10.5) ml/min for females. The weight/creatinine formula had a sensitivity of 91% and a specificity of 80% to detect a clearance below 50 ml/min.
  
  
  CONCLUSIONS
  The weight/creatinine formula underestimates the clearance for normal creatinine values but fits quite well for creatinine levels between 1.5-3 mg/dl, mainly in patients older than 60 years. Although the estimation of clearance through this formula could be inaccurate, in most cases this is clinically irrelevant. Moreover, such a simple formula could avoid potential mistakes appearing at the time of evaluating renal function only by the serum creatinine.
authors.affiliation: Servicio de Nefrología. Hospital Universitario Valdecilla. Santander. España. neffg@humv.es
authors.forename: Gema
authors.initials: G
authors.lastname: Fernández-Fresnedo
authors.forename: Angel Luis
authors.initials: AL
authors.lastname: Martín de Francisco
authors.forename: Emilio
authors.initials: E
authors.lastname: Rodrigo Calabia
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Ruiz San Millán
authors.forename: Saturnino
authors.initials: S
authors.lastname: Sanz de Castro
authors.forename: Manuel
authors.initials: M
authors.lastname: Arias Rodríguez
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001835:Body Weight; D002648:Child; D003404:Creatinine / Q000097:blood*; D005194:Family Practice; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D051437:Renal Insufficiency / Q000097:blood / Q000175:diagnosis*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D003404:Creatinine
vernacular_title: Valoración del filtrado glomerular mediante la fórmula peso/creatinina.