Strong interference of hemoglobin concentration on CSF total protein measurement using the trichloroacetic acid precipitation method.
ABSTRACT Among other methods, trichloroacetic acid precipitation is used to quantify total protein in cerebrospinal fluid (CSF).
We analyzed the influence of hemoglobin on total protein concentration assayed by the trichloroacetic acid method and compared the results to the benzethonium chloride method.
Four CSF samples were spiked with different amounts of hemoglobin, leading to overestimation of protein concentration when assayed by the trichloroacetic acid method. Using the benzethonium chloride method, measurement of protein concentration was minimally disturbed. In addition, albumin and total protein concentrations were measured in 135 clinical samples. The total protein/albumin ratio remained constant when protein was measured with the benzethonium chloride method, while ratios increased when protein was assayed by the trichloroacetic acid method.
Strong interference by hemoglobin leads to overestimation of the total protein concentration in CSF when assayed by the trichloroacetic acid method and may lead to false conclusions when evaluating the blood-brain barrier.
- SourceAvailable from: clinchem.orgClinical Chemistry 02/2006; 52(1):152-3. · 7.15 Impact Factor
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ABSTRACT: We describe a rapid method for the routine determination of protein in cerebrospinal fluid (CSF) and in urine using laser nephelometer. The relative light scattering (RLS) resulting from the interaction of trichloroacetic acid (TCA) and protein is linearly related to the concentration of protein from 0.01 to 6.0 g/L. Precision studies indicate that the day-to-day coefficient of variation (CV) for two CSF controls (0.32 and 0.64 g/L) were 6.4% and 4.9%, respectively. The day-to-day CV's for two urine controls (0.39 and 0.84 g/L) were 5.8% and 2.9%, respectively. Correlation studies with a manual spectroturbidimetric method revealed a correlation coefficient of 0.99 for both CSF and urine specimens. The proposed method, which uses a smaller sample size, is fast and provides greater sensitivity at low ranges due to the ability to increase the sensitivity by the laser nephelometer.Journal of the Formosan Medical Association 01/1991; 89(12):1067-71. · 1.00 Impact Factor
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ABSTRACT: The effect of hemolysis on several assays performed with the Hitachi 717 was quantified by relating the amount of error to the concentration of hemoglobin. Hemolysis interference was judged clinically significant when analyte concentration varied by > 10% from the initial value. Hemolysis interference was significant for alkaline phosphatase, aspartate aminotransferase, alpha-amylase, bilirubin, creatine kinase, gamma-glutamyltransferase, lactate dehydrogenase, lactate dehydrogenase-1, potassium, and theophylline assays. Error (expressed in absolute terms) was linearly dependent on hemoglobin concentration and independent of the initial analyte concentration in each case, except for bilirubin and theophylline, where multiple regression analysis was required to quantify the effect. Relative error was dependent on the initial analyte concentration in all cases. Correction formulas were calculated from linear regression of absolute error vs hemoglobin concentration. Clinical application of correction formulas and mechanisms of hemolysis interference for each assay are discussed.Clinical Chemistry 10/1993; 39(9):1804-10. · 7.15 Impact Factor