Arch Dis Child 2001;85:155-157
( August )
Article
Dipstick measurements of urine specific gravity are unreliable
A S de Buys Roessingh, A Drukker, J-P Guignard
Renal Unit,
Department of Paediatrics, University Medical Centre (CHUV), CH-1011
Lausanne, Switzerland
Correspondence to: Prof. Guignard
Jean-Pierre.Guignard{at}chuv.hospvd.ch
Accepted 21 March 2001
AIM
To evaluate the reliability of
dipstick measurements of urine specific gravity (U-SG).
METHODSFresh 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).
RESULTSThe correlations between
the visual U-SG dipstick measurements and U-SG determined by a
refractometer and the comparison of Clinitek®-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.
CONCLUSIONSAmong the bedside
determinations, only refractometry gives reliable U-SG results.
Dipstick U-SG measurements should be abandoned.
Keywords:
urine specific gravity;
dipstick urinalysis
© 2001 by Archives of Disease in Childhood
