Evaluation of an automated urine chemistry reagent‐strip analyzer

Lott, John; Johnson, William Raymond; Luke, Karl E.

doi:10.1002/jcla.1860090311

Cited by 13 publications

(3 citation statements)

References 4 publications

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“…The accuracy of the osmometer is ±2 mosm kg H 2 O -1 between 0 and 400 mosm kg H 2 O -1 . For the measurement of urine specific gravity, the Clinitek Atlas Ò device agrees within ±0.002 SG units in 95 % of the samples with a total solids meter (Lott et al 1995). Percentage change in plasma volume was determined according to Strauss et al (1951).…”

Section: Blood and Urine Analysesmentioning

confidence: 99%

Changes in body composition in triathletes during an Ironman race

et al. 2013

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The loss in lean mass was explained by a decrease in muscle density, as an indicator of glycogen loss, and increases in several indicators for dehydration. The measurement of body composition with DXA and pQCT before and after an Ironman triathlon provided exact values for the loss in fat and lean mass. Consequently, these results yielded more detailed insights into tissue catabolism during ultra-endurance exercise.

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Section: Blood and Urine Analysesmentioning

confidence: 99%

Changes in body composition in triathletes during an Ironman race

et al. 2013

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“…While some reliable digital portable models are now available, pH meters must be calibrated regularly, and they are more expensive than pH strips (also known as 'pH paperÕ or 'pH dipstripsÕ). The accuracy of pH strips for urine pH measurements compared to the pH meter has been assessed in studies on animals and humans with varied results [11][12][13][14]. There have also been some attempts to estimate urine pH levels based on several factors that can influence its value: diet composition, body surface area, acute water load, exercise (lactic metabolism), and a number of medications [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Measurement of urine pH for epidemiological studies on bladder cancer

et al. 2007

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Methods for efficiently identifying subjects with constantly acidic pH in epidemiological and clinical studies have not been assessed. We recruited 30 volunteers to estimate the minimum number of urine pH measurements using pH strips needed to identify subjects with "constantly acidic urine pH". Spearman's correlation coefficients between urine pH measured with a pH meter and with the four pH strips ranged from 0.94 to 0.95 (p < 0.001 for all four strips). Overall agreement within +/-0.5 pH units between the four strips and the pH meter ranged from 62.2% to 74.4%. When using a spot urine sample from a single morning to classify participants with respect to their urine pH, 80% of individuals fell into the acidic urine pH (pH equal to or lower than 6.0) group. When we required subjects to have urine pH equal to or lower than 6.0 in six consecutive AM spot urine samples and seven spot PM urine samples, only 20% of participants fulfilled this criterion. Measuring urine pH twice a day (early in the morning and early in the evening) during four consecutive days classified individuals in the same way as two daily measurements for one week. A single pH measurement from a spot urine sample is not reliable to identify individuals with constantly acidic pH. Morning and evening urine pH measurements with pH strips during four consecutive days identify individuals with constantly acidic urine pH individuals as well as one week of measurements, and thus might be useful to identify subjects with constantly acidic urine pH in epidemiological and clinical studies.

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“…Instead of utilizing a chemical reaction, one of the latest automated urine chemistry reagent strip analyzers has incorporated a fibro-optic refractive index technology for SG measurement [48]. This method is claimed to be more accurate than the solid phase polyelectrolyte method of the reagent strip.…”

Section: Discussionmentioning

confidence: 99%

Measurement of urinary concentration: a critical appraisal of methodologies

Chadha

Garg

Alon

2001

Pediatric Nephrology

161

143

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The measurement of urine concentration provides information concerning the kidney's ability to appropriately respond to variations in fluid homeostasis. It also assists in the interpretation of other tests performed on the same urine specimen. The gold standard of estimating urinary concentration is the measurement of its osmolality; however, this procedure is not readily available to the practicing physician. Therefore, urine concentration is usually determined by measurement of its specific gravity (SG), which provides a fair estimate of urine osmolality. Over the years numerous tests have been developed to measure urine SG in a simple, quick, reliable and easily available method. These tests measure SG either directly (e.g., gravimetry) or by indirect methods (e.g., refractometry and reagent strip). All these tests have certain limitations based on their underlying physical principles. Specific gravity as measured by refractometry is influenced by proteinuria, such that for each 10 g/l protein the SG increases by 0.003. SG is also influenced by glucosuria such that it increases by approximately 0.002 per 10 g/l glucose when compared with urinary osmolality. Unlike osmolality, which is only affected by the number of particles, refractometry is affected by number, mass and chemical structure of the dissolved particles; hence large molecules like radiographic contrast or mannitol will increase SG relative to osmolality. The reagent strip is minimally affected by glucose, mannitol or radiographic contrast. However, it is affected by urinary pH such that only urine in the pH range of 7.0-7.5 can be correctly interpreted. The measurement of SG by reagent strip is based on the ionic strength of the urine and thus is significantly affected by the ionic composition of the urine and by proteins which have an electric charge in solution. In our experience, SG measured by the refractometer is consistently more accurate than the reagent strip. For the clinician who is interpreting urine SG results, it is important to be aware of these limitations and understand the reasons for possible potential errors of each particular method.

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Evaluation of an automated urine chemistry reagent‐strip analyzer

Cited by 13 publications

References 4 publications

Changes in body composition in triathletes during an Ironman race

Changes in body composition in triathletes during an Ironman race

Measurement of urine pH for epidemiological studies on bladder cancer

Measurement of urinary concentration: a critical appraisal of methodologies

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