Lasho, Michael A.

Abstract Background Capillary self-collection (CSC) devices allow patients to collect blood samples at home, potentially reducing outpatient phlebotomy visits. This study aimed to (a) assess the patient experience with multiple commercially available CSC devices; (b) determine which laboratory tests are commonly ordered together, which could reduce the need for appointments; and (c) evaluate the analytical performance of these tests using CSC samples. Methods User experience for 3 CSC devices was evaluated. Clinical feasibility was determined by comparing test results in paired sera collected by venipuncture (VP) and CSC devices. VP samples were centrifuged within 2 h and tested immediately. CSC sera were centrifuged and tested both immediately and after delayed processing to simulate shipping temperature extremes (−20°C or 40°C). Basic metabolic panel, lipid panel, thyroid function cascade, and prostate-specific antigen were evaluated. Differences between VP and CSC collections were characterized according to their statistical and clinical differences. Results Patients reported CSC devices were easy to use and painless. Clinically significant differences between VP and CSC sera processed immediately were limited to potassium and bicarbonate. Following delayed processing of CSC serum samples (48 h at room temperature), clinically significant differences in potassium, bicarbonate, and glucose were observed. Frozen samples could not be analyzed. A 48 h delay at 40°C caused clinically significant differences in all analytes except creatinine, lipid panel, prostate-specific antigen, and the thyroid cascade. Conclusion Potassium, bicarbonate, and glucose were not stable at room temperature in CSC sera. CSC serum specimens may be a viable option but require analyte-specific evaluation and consideration of transportation conditions.

Abstract Background Hemolysis, a common pre-analytical interferent in clinical laboratory testing, can significantly affect accuracy and reliability of laboratory results. One test particularly susceptible to interference is direct bilirubin (D-bil). For example, during December 2024, 40% (500/1239) of specimens rejected due to hemolysis were orders for D-bil. The recently released Roche (Roche Diagnostics) direct bilirubin reagent (BILD2) has a lower threshold for hemolysis (H-index [HI]=25)) than the previous generation (HI=30). The aims of our study were to (1) establish concentration-specific hemolysis thresholds for D-bil and (2) investigate the instrument’s reduced volume function (dilution) as a possible mitigation strategy for samples with hemolysis indices exceeding the established thresholds. Methods Residual serum specimens from physician-ordered D-bil testing were used and analyzed on Roche cobas c701 and c501 analyzers. The instrument’s decreased volume function, intended for results outside the measuring range, was used as a 1:2 dilution and validated using 9 non-hemolyzed negative control specimens with D-bil results from 9.8-13.4 mg/dL. Recovery within 10% neat value was considered acceptable. EDTA whole blood was used to prepare hemolysate pools by washing red cells and lysing by freezing (-80 °C). Twenty-six serum pools with varying D-bil concentrations (0.2-3.4 mg/dL) were prepared. Each pool was split into 10 aliquots and spiked with increasing amounts of hemolysate, not exceeding 10% serum to interferent ratio. The decreased volume function (dilution) was utilized on a subset of the hemolysate-spiked aliquots (N=55) with D-bil results from 0.2-2.5 mg/dL. HI values were estimated to be 50% of neat HI due to the instrument’s inability to measure indices on specimens tested with the decreased volume function. Acceptance criteria for experiments utilizing hemolyzed specimens were ±0.1 mg/dL or 20% of neat sample. Results All non-hemolyzed specimens tested with the decreased volume function passed within acceptance criteria with average recovery of 109% (range: 106-110%) from undiluted specimens. Serum pools with D-bil <0.3 mg/dL (N=7) spiked with hemolysate (HI range: 7-191) had an average difference of -0.1 mg/dL (range: -0.2-0.0 mg/dL) from non-hemolyzed pools, D-bil pools 0.4-0.9 mg/dL (N=10; HI range: 6-173) had an average difference of -0.2 mg/dL (range: -0.5-0.0 mg/dL), and D-bil pools >1.0 mg/dL (N=9; HI range: 5-182) had an average difference of -20.7% (range –45.5-0.0%). Serum pools with D-bil <0.3 mg/dL (N=23; HI range: 43-191) tested using the decreased volume function had an average difference –0.1 mg/dL (range: -0.2-0.0 mg/dL; HI range: 22-96) from the non-hemolyzed specimens, D-bil pools 0.4-0.9 mg/dL (N=20; HI range: 39-173) had an average difference -0.1 mg/dL (-0.3-0.0 mg/dL; HI range: 19-86), and D-bil pools >1.0 mg/dL (N=12; HI range: 37-182 ) had an average difference of -0.2 mg/dL (-0.5-0.2 mg/dL; HI range: 19-91). Conclusion We established a new hemolysis interference threshold of 75 for samples with D-bil <0.3 mg/dL. Using the decreased volume function, we expanded the hemolysis interference threshold to HI=100 for specimens =0.3 mg/dL. All specimens with HI>100 will result in a recollection. With these changes, we estimate that we can reduce our D-bil recollections by up to 6% over six months.

Abstract Objectives The aims of this study were to (1) establish the maximum allowable interference limits for hemolysis, lipemia, and icterus for chemistry analytes tested in body fluid samples and (2) assess the effectiveness of serial dilution to mitigate spectral interferences. Methods Residual body fluids from clinically ordered testing were mixed (<10% by volume) with stock solutions of interferent (spiked) and compared with a control spiked with an equal volume of 0.9% saline. The analytes were measured on the Roche cobas c501 instrument. Difference and percentage difference were calculated and compared with allowable total error limits. A subset of samples were serially diluted with 0.9% saline. Mean (SD) difference and percentage difference were calculated. Results The interference thresholds were lower than the package insert for lactate dehydrogenase, cholesterol, triglycerides, and total protein for hemolysis; amylase, cholesterol, and total protein for icterus; and albumin for lipemia. Only cholesterol and triglyceride results returned to baseline upon dilution of icteric samples. Conclusions Interference thresholds in body fluids were lower than blood for 6 analytes. Diluting interferences that surpass these limits does not produce reliable results that are comparable to the baseline results before spiking in the interferent.

Abstract Background Total protein is measured in serum and body fluids as part of routine evaluations of general nutritional status and differentiating exudative and transudative effusions. Spectral interference thresholds for bilirubin (e.g., icterus) is set by assay manufacturers to prevent inaccurate results from being reported. The Roche Cobas serum total protein assay package insert states no significant interference from bilirubin up to an icterus (I) index of 20. Body fluids tend to have lower total protein concentrations; therefore, thresholds were derived during prior validation studies and set to I = 10, a threshold that is exceeded routinely. Laboratories can mitigate some interferences by recollecting (e.g., hemolysis) or ultracentrifuging (e.g., lipemia) specimens. Serial dilutions are another option used; however, it is imperative that the laboratory understands the mechanism of interference and can demonstrate that it is mitigated by sample dilution. The aim of this study was to investigate whether bilirubin interference can be mitigated by sample dilution in pleural fluid, peritoneal fluid, and serum specimens. Methods Residual clinically ordered pleural fluid (n = 3), peritoneal fluid (n = 3), and serum (n = 3) samples submitted for protein testing were split into two equal volume aliquots with concentrations ranging 2.7 to 4.3 g/dL in pleural fluids, 3.9 to 5.4 g/dL in peritoneal fluids, and 3.8 to 11.0 g/dL in serum. One aliquot was spiked (<10% by volume) with a bilirubin conjugate solution (∼1000 mg/dL) to surpass the icterus index threshold (spiked). The second aliquot was spiked with an equal volume of 0.9% saline (control). Total protein was measured on the Roche Cobas c701 instrument in both samples to calculate difference (Spiked-Control). The mean(SD) difference was calculated for each sample type. Each spiked sample was serially diluted (2-fold, 4-fold and 8-fold) with 0.9% saline. Total protein was measured for each diluted sample. Mean(SD) difference was calculated (DilutedX-Control), where X = 2-fold, 4-fold, 8-fold. Linear regression analysis was performed by plotting the measured (x-axis) vs expected (y-axis) total protein concentration. Slope, y-intercept, and R2 were determined from serially diluted samples where the expected concentrations were derived using the spiked concentration to replicate the practice of diluting an icteric sample. Results Bilirubin spiking (average icterus index = 33.5) into pleural fluid, peritoneal fluid, and serum, respectively demonstrated mean(SD) bias (g/dL) = −1.0(0.2), −0.9(0.0), and −0.7(0.0). Subsequent 2-fold dilution demonstrated mean(SD) bias (g/dL) = −1.0(0.2), −1.0(0.0), and −0.8(0.1), 4-fold dilution with mean(SD) bias (g/dL) = −1.1(0.2), −1.0(0.0), and -1.0(0.1), and 8-fold dilution with mean(SD) bias (g/dL) = −1.3(0.2), −1.0(0.0), and −1.4(0.1). Diluting pleural, peritoneal, and serum samples, respectively spiked with bilirubin resulted in slope = 0.99, 1.00, and 0.99; y-intercept = 0.04, 0.01, and 0.07; R2 = 0.99, 0.99, 0.99. Conclusion The dilutions exhibited a linear dilution response, however the dilution results never returned to baseline (non-spiked) concentration. Laboratories should exercise caution when conducting serial dilutions to diminish bilirubin interference in samples when measuring total protein as the mechanism of interference does not appear to be reversible by dilution. This behavior was demonstrated in both body fluids and serum.

COVID-19 convalescent plasma (CCP) was one of the first therapeutic options available for the treatment of SARS-CoV-2 infections and continues to be used selectively for immunosuppressed patients. Given the emergence of novel SARS-CoV-2 variants which are resistant to treatment with available monoclonal antibody (MAb) therapy, CCP remains an important therapeutic consideration.

Longitudinal studies assessing durability of the anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) humoral immune response have generated conflicting results. This has been proposed to be due to differences in patient populations, the lack of standardized methodologies, and the use of assays that measure distinct aspects of the humoral response.