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Dipstick measurements of urine specific gravity are unreliable

2001; BMJ; Volume: 85; Issue: 2 Linguagem: Inglês

10.1136/adc.85.2.155

1468-2044

Anthony de Buys Roessingh, Alfred Drukker, Guignard Jp,

Neonatal Health and Biochemistry

AIM 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 ® -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.