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Comparison of Laser-Probe and Photometric Determination of the Urinary Crystallization Risk of Calcium Oxalate

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Published/Copyright: June 1, 2005
Clinical Chemistry and Laboratory Medicine (CCLM)
From the journal Volume 40 Issue 6

Abstract

A variety of equipment is used for the observation of precipitation processes which occur in urinary samples. The Bonn-Risk-Index, a measure of the calcium oxalate crystallization risk of human urine, has been developed with the use of an in-line laser-probe gauge. For basic research or in clinical laboratories, however, this instrument, which fulfills industrial requirements for the evaluation of particle size distributions, is not widely available. The evaluation of an alternative method to determine the Bonn-Risk-Index based on a more commonly available apparatus would therefore be useful.

In vitro crystallization experiments with 124 native urine samples from stone-forming and non-stone forming individuals were performed in order to determine their crystallization risk according to the Bonn-Risk-Index approach. The onset of an induced urinary crystallization was detected by simultaneous sample monitoring with an in-line laser-probe and a conventional dip-in photometer. A decrease of the sample's relative light transmissivity from initially 100% to 98% was assumed to be a reliable photometer-based criterion to indicate that crystallization actually began. The laser-probe signal was set as the reference measure.

Linear regression analysis of the results of the laser-probe and the photometer-based Bonn-Risk-Index determinations reveals a significant and close correlation between the two measures. Method comparison by statistical evaluation shows i) that no significant deviation from linearity exists and ii) that both methods are statistically identical. The differences in the results are small enough to be confident that the photometer can be used in place of the laser-probe for clinical purposes.

The photometer is a reliable, easy-to-use and cost-effective method for the determination of a triggered crystallization event in a urine sample. The assumed 98% criterion allows the determination of the Bonn-Risk-Index with adequate accuracy.

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Published Online: 2005-06-01
Published in Print: 2002-06-21

Copyright (c) 2002 by Walter de Gruyter GmbH & Co. KG

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https://doi.org/10.1515/CCLM.2002.102

Articles in the same Issue

  1. IFCC Primary Reference Procedures for the Measurement of Catalytic Concentrations of Enzymes – the New Concept
  2. Allele Frequency of the G→T Mutation of the Col1A1 Gene Analyzed by an ARMS-PCR in Osteoporotic Subjects with Femoral Neck Fractures
  3. Vitamin Supplementation Normalizes Total Plasma Homocysteine Concentration but Not Plasma Homocysteine Redox Status in Patients with Acute Coronary Syndromes and Hyperhomocysteinemia
  4. Mutation Analysis of the MPZ and PMP22 Genes in Croatian Patients
  5. Dynamic Equilibrium between Protein S and C4b Binding Protein Is Important for Accurate Determination of Free Protein S Antigen
  6. Immunoassay of Anti-Thyroid Autoantibodies: High Analytical Variability in Second Generation Methods
  7. The Measurement of Insulin-like Growth Factor-I (IGF-1) Concentration in Random Urine Samples
  8. Urinary Bikunin Determination Provides Insight into Proteinase/Proteinase Inhibitor Imbalance in Patients with Inflammatory Diseases
  9. Breath Markers and Soluble Lipid Peroxidation Markers in Critically Ill Patients
  10. Comparison of Laser-Probe and Photometric Determination of the Urinary Crystallization Risk of Calcium Oxalate
  11. Comparison of First Trimester, Second Trimester and Integrated Downs Syndrome Screening Results in Unaffected Pregnancies
  12. Anti-Phospholipid Antibodies in Diabetes Mellitus
  13. Alteration of Serum Enzymes in Primary Hypothyroidism
  14. The Changes of Superoxide Dismutase, Catalase and Glutathione Peroxidase Activities in Erythrocytes of Active and Passive Smokers
  15. Internal Quality Control System for Non-Stationary, Non-Ergodic Analytical Processes Based upon Exponentially Weighted Estimation of Process Means and Process Standard Deviation
  16. Evaluation of Commutability of Control Materials
  17. IFCC Primary Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes at 37°C. Part 1. The Concept of Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes
  18. IFCC Primary Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes at 37°C. Part 2. Reference Procedure for the Measurement of Catalytic Concentration of Creatine Kinase
  19. IFCC Primary Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes at 37°C. Part 3. Reference Procedure for the Measurement of Catalytic Concentration of Lactate Dehydrogenase
  20. Meetings and Awards
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