title: Microalbumin measurement alone or calculation of the albumin/creatinine ratio for the screening of hypertension patients?
abstract: BACKGROUND
  Spot urine sampling seems to be a reliable screening method for the detection of microalbuminuria in hypertensive patients. It remains unclear whether microalbumin measurement alone or calculation of the albumin/creatinine ratio (ACR) are more reliable for the detection of microalbuminuria in non-selected hypertensive patients.
  
  
  METHODS
  Following collection of a spot, midstream urine sample, urine was collected for 24 h for the measurement of microalbumin in 264 hypertensive patients. We compared microalbumin concentration in the spot urine with microalbumin measured in the 24-h urine sample and examined the utility of the ACR in evaluating microalbuminuria in hypertensive patients. Pathologic microalbuminuria was assumed when the microalbumin concentration exceeded 30 mg/l in the 24-h urine sample. Diagnostic performance is expressed in terms of specificity, sensitivity, positive (PPV) and negative predictive value (NPV), and area under receiver operating characteristics curve (AUC).
  
  
  RESULTS
  A total of 47 samples (17.8%) showed pathologic microalbuminuria in the 24-h urine sample. The diagnostic performance expressed as AUC was 0.94 (95% CI 0.90-0.98) for microalbumin measurement alone and 0.94 (95% CI 0.89-0.97) for ACR. The PPV and NPV were 44.2 and 97.9% for microalbumin measurement alone. ACR revealed a PPV of 29.3% and a NPV of 96.2% for males and 42.9 and 98% for females, if a cut-off value of 2.5 mg/mmol for males and of 4.0 mg/mmol for females was used.
  
  
  CONCLUSIONS
  The ACR did not provide any advantage compared with microalbumin measurement alone, but requires an additional determination of creatinine and the use of gender-specific cut-off values. Therefore, measurement of microalbuminuria alone in the spot urine sample is more convenient in daily clinical practice and should be used as the screening method for hypertensive patients.
authors.affiliation: Department of Emergency Medicine, University of Vienna, Waeringer Guertel 18-20, A-1090 Vienna, Austria.
authors.forename: Ulla
authors.initials: U
authors.lastname: Derhaschnig
authors.forename: Harald
authors.initials: H
authors.lastname: Kittler
authors.forename: Christian
authors.initials: C
authors.lastname: Woisetschläger
authors.forename: Andreas
authors.initials: A
authors.lastname: Bur
authors.forename: Harald
authors.initials: H
authors.lastname: Herkner
authors.forename: Michael M
authors.initials: MM
authors.lastname: Hirschl
mesh_terms: D000328:Adult; D000368:Aged; D000419:Albuminuria / Q000175:diagnosis*; D003404:Creatinine / Q000652:urine*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis* / Q000652:urine; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity
chemical_list: D003404:Creatinine