Urinary specific gravity--comparative measurements using reagent strips and refractometer in 340 morning urine samples

The specific gravity of urine (SG) indicates the number and weight of solute particles in urine; its measurement is helpful in interpreting proteinuria detected by dipstick tests and in monitoring adequate hydration in patients with nephrolithiasis. Four methods for measuring SG or osmolality of uri...

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Bibliographic Details
Published inSchweizerische Rundschau fur Medizin Praxis = Revue suisse de medecine Praxis Vol. 82; no. 4; p. 112
Main Authors Siegrist, D, Hess, B, Montandon, M, Takkinen, R, Lippuner, K, Jaeger, P
Format Journal Article
LanguageGerman
Published Switzerland 26.01.1993
Subjects
Female
Humans
Male
Osmolar Concentration
Reagent Strips
Refractometry
Sensitivity and Specificity
Specific Gravity
Urine - chemistry
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Summary:The specific gravity of urine (SG) indicates the number and weight of solute particles in urine; its measurement is helpful in interpreting proteinuria detected by dipstick tests and in monitoring adequate hydration in patients with nephrolithiasis. Four methods for measuring SG or osmolality of urine are currently available (depression of the freezing-point, urometry, refractometry, cation exchange on a reagent strip). Using a recently developed reagent strip, we have measured SG in morning urines of 340 non-selected outpatients and compared the results with SG measurements by refractometry of the same urines. In 86.2% of all urines, a good positive correlation between SG measured by reagent strip and refractometry was noted (r = 0.913, p = 0.0001). In 13.8% of the urines, however, the SG measured by reagent strip deviated by more than +/- 5 from the value obtained by refractometry; in 90% of these urines, glucosuria (reagent strip values too low or too high), proteinuria (values too high), or bacteriuria/leukocyturia (values too low or too high) could be found. In alkaline urine (pH > 7.0), SG values obtained by reagent strip have to be corrected by +5.
ISSN:1013-2058