The Refractometric Determination of Albumin, Globulin, and Nonprotein

Tranter, Charles L.; Rowe, Albert H.

doi:10.1001/jama.1915.02580170021005

Cited by 9 publications

(1 citation statement)

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“…Refractometry has also been used in the assessment of serum and/or plasma total protein (TP) measurements [2] , [3] , [4] , [5] . In this capacity, refractometer scales are calibrated against normal serum, with the general assumption that many non-protein solutes (e.g.…”

Section: Introductionmentioning

confidence: 99%

Clinical performance evaluation of total protein measurement by digital refractometry and characterization of non-protein solute interferences

Hunsaker

Wyness

Snow

et al. 2016

Practical Laboratory Medicine

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ObjectivesRefractometric methods to measure total protein (TP) in serum and plasma specimens have been replaced by automated biuret methods in virtually all routine clinical testing. A subset of laboratories, however, still report using refractometry to measure TP in conjunction with serum protein electrophoresis. The objective of this study was therefore to conduct a modern performance evaluation of a digital refractometer for TP measurement.Design and methodsPerformance evaluation of a MISCO Palm Abbe™ digital refractometer was conducted through device familiarization, carryover, precision, accuracy, linearity, analytical sensitivity, analytical specificity, and reference interval verification. Comparison assays included a manual refractometer and an automated biuret assay.ResultsCarryover risk was eliminated using a demineralized distilled water (ddH2O) wash step. Precision studies demonstrated overall imprecision of 2.2% CV (low TP pool) and 0.5% CV (high TP pool). Accuracy studies demonstrated correlation to both manual refractometry and the biuret method. An overall positive bias (+5.0%) was observed versus the biuret method. On average, outlier specimens had an increased triglyceride concentration. Linearity was verified using mixed dilutions of: a) low and high concentration patient pools, or b) albumin-spiked ddH2O and high concentration patient pool. Decreased recovery was observed using ddH2O dilutions at low TP concentrations. Significant interference was detected at high concentrations of glucose (>267 mg/dL) and triglycerides (>580 mg/dL). Current laboratory reference intervals for TP were verified.ConclusionsPerformance characteristics of this digital refractometer were validated in a clinical laboratory setting. Biuret method remains the preferred assay for TP measurement in routine clinical analyses.

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Section: Introductionmentioning

confidence: 99%