Swartchick, Chelsea B.

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 Chronic kidney disease (CKD) is associated with increased blood‐based biomarker concentrations, potentially confounding their utility in Alzheimer's disease (AD) evaluation. While plasma phosphorylated tau217 ( p ‐tau217) is elevated in the presence of amyloid related pathology, amyloid beta 1‐42 (Aβ42) is decreased. We investigated the association of plasma p ‐tau217, non‐phosphorylated tau217 (np‐tau217), Aβ42, Aβ40, as well as the Aβ42/Aβ40 and p ‐tau217/Aβ42 ratios, versus decreased estimated glomerular filtration rate (eGFR in mL/min/1.73 m 2 ) in individuals without amyloid pathology. Method This study included participants with CKD stages 1‐2 (eGFR 60‐98, n = 50), and stages 3‐4 (eGFR 25‐59, n = 33), who were Pittsburgh 11 C‐Compound B amyloid‐PET negative (Centiloid of < 25). Plasma p ‐tau217, np‐tau217, Aβ42, and Aβ40 were measured by immunoprecipitation mass spectrometry (C 2 N Diagnostics). %p‐tau217 [( p ‐tau217/np‐tau217) x100], Aβ42/Aβ40 ratio, and p ‐tau217/Aβ42 ratio were calculated. Log‐Log (power function) best‐fit regression analysis was used to quantitatively predict effects of changes in eGFR (2021 CKD‐EPI equation) versus each single analyte or ratio (Figure 1). Result Selected best‐fit analyte equations versus eGFR are shown in Table 1. The predicted percent increase of p ‐tau217 as eGFR decreases from 60 to 45 was 52% (95% CI: 30–78%). Significantly smaller increases of 16% were predicted for Aβ42 (95% CI: 12–21%), and 19% for Aβ40 (95% CI: 16–23%) over the same eGFR range. The best‐fit predicted increase for the p ‐tau217/Aβ42 ratio and %p‐tau217 as eGFR decreases from 60 to 45 was 31% (95% CI: 12–53%), and 19% (95% CI: 2–38%), respectively. While not recommended for assessment of amyloid pathology, the Aβ42/Aβ40 ratio did not exhibit a predicted increase (‐2.3% decrease, 95% CI: ‐5.2–0.6%) versus decreasing eGFR from 60 to 45. Conclusion The use of either %p‐tau217 or the p ‐tau217/Aβ42 ratio (to a lesser degree) reduced the confounding effects of decreasing eGFR as compared to p ‐tau217 alone. Aβ42 and Aβ40 exhibited similar reduced predicted increases versus decreasing eGFR as compared to p ‐tau217. Relative to the predicted effects of decreasing eGFR on p ‐tau217 measurements, the p ‐tau217/Aβ42 ratio relative increase was reduced by 40%, while the relative increase was reduced by 63% for %p‐tau217 measurements.

Abstract Background The Oncology Department at our institution requested faster turn-around times (TAT) for chemistry testing. Prior to their request, serum separator tubes (SST) were collected and tested in our core laboratory. To accommodate the request, we added plasma total bilirubin and aspartate aminotransferase (AST) to our stat laboratory test menu with collection in plasma separator tubes (PST). Upon implementation of this testing change, we observed an increase in specimen recollection rates due to hemolysis. We systematically evaluated laboratory testing variables that could have contributed to the increase: pneumatic tube transport path, differences in hemolysis measurements between chemistry analyzer models, and specimen types. Previous studies have demonstrated that lithium heparin plasma specimens are more susceptible to hemolysis than serum. Likewise, patients undergoing chemotherapy or radiation therapy may have fragile red blood cell (RBC) membranes, further complicating the issue. Our study*s objective was to assess the impact of changing from SST to PST collections. We conducted a 3-month pilot study to determine if we could reduce our recollection rates by collecting/testing Rapid Serum Tube (RST), while maintaining plasma TAT. Methods We compared recollection rates for specimens collected from the oncology patients and tested in our core laboratory (SST, May-June 2021), stat laboratory (PST, September-November 2022), pilot period in stat lab (RST, January-March 2023), and post-pilot period in stat lab (PST, May-July 2023). Data were extracted from our laboratory information system and recollection rates were calculated using Tableau (Salesforce, Inc, San Francisco, CA). Analysis was performed in Excel (Microsoft, Redmond, WA) using Student’s t-test, with p &lt; 0.05 defined as statistically significant. Results SST specimens collected from oncology patients and tested in the core lab (May-June 2021) resulted in a recollection rate of 0.17% (4/2341). PST specimens sent to the stat lab (Sept-Nov 2022) had an increased recollection rate of 0.90% (55/6129, p-value &lt; 0.001). During the pilot period when RST tubes were used (Jan-Mar 2023), our recollection rate decreased to 0.19% (11/5801, p-value 0.014). After the pilot period ended and PST tubes were again utilized for testing (May-July 2023), the recollection rate again increased to 0.34% (22/6500, p-value 0.019). Conclusion Rapid TAT of laboratory results within specialized-care settings, such as a cancer treatment clinic, is necessary to provide patients with the most effective and personalized treatment regimens. Hemolysis presents a challenge as it generates an analytical issue with the release of contents from RBCs that may spuriously affect the concentration of the analyte being measured, delaying result reporting due to the need for specimen recollection. The data from our study highlight the utility of rapid serum tubes. Not only did they achieve stat TAT that was observed with the use of PST, but they also decreased specimen recollection rates that mirror the low rates observed with the use of SST. Thus, this technology may be an excellent replacement for standard SST when specimen integrity is critical to rapidly reporting accurate test results.