Evaluation and analytical validation of a handheld digital refractometer for urine specific gravity measurement

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• 作者：Sara P. Wyness^a ; Joshua J.H. Hunsaker^a ; Taylor M. Snow^a ; Jonathan R. Genzen^a ; ^b ; ^{jonathan.genzen@path.utah.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：ACSM ; American College of Sports Medicine ; ALB ; albumin ; AMR ; analytical measurement range ; ARUP ; Associated Regional & University Pathologists ; Cl ; chloride ; CLSI ; Clinical & Laboratory Standards Institute ; CR ; creatinine ; CV ; coefficient of variation ; ddH2O ; demineralized distilled water ; FDA ; Food and Drug Administration ; GLU ; glucose ; IRB ; Institutional Review Board ; K+ ; potassium ; LIMS ; laboratory information management system ; LLMI ; lower limit of the measuring interval ; LOB ; limit of blan
• 刊名：Practical Laboratory Medicine
• 出版年：2016
• 出版时间：1 August 2016
• 年：2016
• 卷：5
• 期：Complete
• 页码：65-74
• 全文大小：1154 K

文摘

Refractometers are commonly used to determine urine specific gravity (SG) in the assessment of hydration status and urine specimen validity testing. Few comprehensive performance evaluations are available demonstrating refractometer capability from a clinical laboratory perspective. The objective of this study was therefore to conduct an analytical validation of a handheld digital refractometer used for human urine SG testing.

Design and methods

A MISCO Palm Abbe™ refractometer was used for all experiments, including device familiarization, carryover, precision, accuracy, linearity, analytical sensitivity, evaluation of potential substances which contribute to SG (i.e. “interference”), and reference interval evaluation. A manual refractometer, urine osmometer, and a solute score (sum of urine chloride, creatinine, glucose, potassium, sodium, total protein, and urea nitrogen; all in mg/dL) were used as comparative methods for accuracy assessment.

Results

Significant carryover was not observed. A wash step was still included as good laboratory practice. Low imprecision (%CV, <0.01) was demonstrated using low and high QC material. Accuracy studies showed strong correlation to manual refractometry. Linear correlation was also demonstrated between SG, osmolality, and solute score. Linearity of Palm Abbe performance was verified with observed error of ≤0.1%. Increases in SG were observed with increasing concentrations of albumin, creatinine, glucose, hemoglobin, sodium chloride, and urea. Transference of a previously published urine SG reference interval of 1.0020–1.0300 was validated.

Conclusions

The Palm Abbe digital refractometer was a fast, simple, and accurate way to measure urine SG. Analytical validity was confirmed by the present experiments.