title: Dipstick measurements of urine specific gravity are unreliable.
abstract: OBJECTIVE
  To evaluate the reliability of dipstick measurements of urine specific gravity (U-SG).
  
  
  METHODS
  Fresh urine specimens were tested for urine pH and osmolality (U-pH, U-Osm) by a pH meter and an osmometer, and for U-SG by three different methods (refractometry, automatic readout of a dipstick (Clinitek-50), and (visual) change of colour of the dipstick).
  
  
  RESULTS
  The correlations between the visual U-SG dipstick measurements and U-SG determined by a refractometer and the comparison of Clinitek((R))-50 dipstick U-SG measurements with U-Osm were less than optimal, showing very wide scatter of values. Only the U-SG refractometer values and U-Osm had a good linear correlation. The tested dipstick was unreliable for the bedside determination of U-SG, even after correction for U-pH, as recommended by the manufacturer.
  
  
  CONCLUSIONS
  Among the bedside determinations, only refractometry gives reliable U-SG results. Dipstick U-SG measurements should be abandoned.
authors.affiliation: Renal Unit, Department of Paediatrics, University Medical Centre (CHUV), CH-1011 Lausanne, Switzerland.
authors.forename: A S
authors.initials: AS
authors.lastname: de Buys Roessingh
authors.forename: A
authors.initials: A
authors.lastname: Drukker
authors.forename: J P
authors.initials: JP
authors.lastname: Guignard
mesh_terms: D006801:Humans; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D019095:Point-of-Care Systems / Q000592:standards; D011933:Reagent Kits, Diagnostic / Q000592:standards*; D012031:Refractometry; D015203:Reproducibility of Results; D013046:Specific Gravity; D016482:Urinalysis / Q000379:methods*
chemical_list: D011933:Reagent Kits, Diagnostic