Measurement of Urine Relative Density Using Refractometer and Reagent Strips
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Romolo M. Dorizzi
Abstract
The relative density of urine is the ratio of its density to that of water and depends on both the number and weight of solute particles in the sample, while osmolality depends only on the number of solute particles. Water metabolism is regulated by the interaction of the renal medullary countercurrent system with the circulating levels of antidiuretic hormone and thirst. The concentration of solids in urine can be measured by weighing, hydrometry, oscillations of a capillary tube, refractometry and reagent strip. These techniques, interrelated but not identical, are commonly used in hospital laboratories and in clinical wards. We compared the results obtained in 1725 urine samples of inpatients and outpatients using an automated refractometer to those obtained using two visually read dip stick tests. The correlation coefficients (Super Aution analyser vs. Aution Sticks 10 EA, Aution Sticks 10 EA vs. N-Multistix, Super Aution analyser vs. N-Multisticks were 0.663, 0.645 and 0.514, respectively) and the great dispersion of mountain plots demonstrates that different techniques are not interchangeable in the measurement of relative density. Since the results obtained after discarding the samples with pH higher than 7 and those containing glucose or protein were very similar to the ones reported above, the role of these interferents appears negligible in inducing the discrepancy.
Copyright © 1999 by Walter de Gruyter GmbH & Co. KG
Articles in the same Issue
- Author Index
- Contents
- Subject Index
- Polymorphisms of Coagulation Factor Genes a Review
- Urinalysis-Challenges by New Medical Needs and Advanced Technologies
- The Automation of Sediment Urinalysis Using a New Urine Flow Cytometer (UF-100™)
- Urinary Microscopy as Seen by Nephrologists
- Measurement of Urine Relative Density Using Refractometer and Reagent Strips
- Dry Chemistry Urinalysis of Pathological Proteinuria
- Physiopathology of Proteinuria and Laboratory Diagnostic Strategy Based on Single Protein Analysis
- Microalbuminuria in Diabetes
- European Multicentre Evaluation of the Super Aution SA-4220 Urinalysis Analyser
- Optimized Detection of DNA Point Mutations by Double Gradient Denaturing Gradient Gel
- Is the Association of Serum Lipase with β2-Microglobulin or C-Reactive Protein Useful for Establishing the Diagnosis and Prognosis of Patients with Acute Pancreatitis?
- Analytical and Clinical Performance of an Automated Immunoassay System (Immulite®) for Estradiol in Serum
- Evaluation of the Activated Partial Thrombo-plastin Time (APTT) Sensitivity to Heparin Using Five Commercial Reagents: Implications for Therapeutic Monitoring
- An Alternative Analysis for Crossover Studies that Accounts for Between-Group Disparities in Drug Response
Articles in the same Issue
- Author Index
- Contents
- Subject Index
- Polymorphisms of Coagulation Factor Genes a Review
- Urinalysis-Challenges by New Medical Needs and Advanced Technologies
- The Automation of Sediment Urinalysis Using a New Urine Flow Cytometer (UF-100™)
- Urinary Microscopy as Seen by Nephrologists
- Measurement of Urine Relative Density Using Refractometer and Reagent Strips
- Dry Chemistry Urinalysis of Pathological Proteinuria
- Physiopathology of Proteinuria and Laboratory Diagnostic Strategy Based on Single Protein Analysis
- Microalbuminuria in Diabetes
- European Multicentre Evaluation of the Super Aution SA-4220 Urinalysis Analyser
- Optimized Detection of DNA Point Mutations by Double Gradient Denaturing Gradient Gel
- Is the Association of Serum Lipase with β2-Microglobulin or C-Reactive Protein Useful for Establishing the Diagnosis and Prognosis of Patients with Acute Pancreatitis?
- Analytical and Clinical Performance of an Automated Immunoassay System (Immulite®) for Estradiol in Serum
- Evaluation of the Activated Partial Thrombo-plastin Time (APTT) Sensitivity to Heparin Using Five Commercial Reagents: Implications for Therapeutic Monitoring
- An Alternative Analysis for Crossover Studies that Accounts for Between-Group Disparities in Drug Response
