Immunoassay interference by a commonly used blood collection tube additive, the organosilicone surfactant silwet L-720.

Background: A small number of immunoassays on several different types of analyzers were recently adversely affected by tube additives in Becton Dickinson (BD) Vacutainer SST, SST II, and Microtainer blood collection tubes. We examined the effect of a commonly used tube surfactant, Silwet L-720, on immunoassays and the mechanism for the interference.

Methods: Immunoassays were performed on serum supplemented with Silwet L-720 on the IMMULITE 2500 and AxSYM analyzers.

Rapid measurement of insulin using the Abbott IMx: application to the management of insulinoma.

Background: Patients with multiple endocrine neoplasia (type 1) often present with multiple pancreatic endocrine tumours, such as insulinomas. A major difficulty in the surgical treatment of such patients is identifying which tumours are functionally active and therefore need to be resected for a cure. The objective of this study was to develop a rapid insulin assay that could be used intraoperatively for identifying insulinomas from pancreatic aspirates.

Kinetic analysis of the rapid intraoperative parathyroid hormone assay in patients during operation for hyperparathyroidism.

Background: Rapid intraoperative parathyroid hormone (RI-PTH) assay is used to guide adequacy of resection during operation for hyperparathyroidism. We compared the RI-PTH assay (15 minutes) with a standard PTH assay, determined whether the PTH half-life varied between patients, and constructed a kinetic analysis of the RI-PTH data.

Methods: Forty-five patients with hyperparathyroidism had blood sampled at baseline and at times after parathyroid resection.

Assessment of monoethylglycinexylidide as measure of liver function for patients with chronic viral hepatitis.

The liver metabolizes lidocaine by oxidative deethylation to form monoethylglycinexylidide (MEGX), an analyte proposed as an index of liver function. We determined MEGX and lidocaine serum concentrations with the TDx (Abbott Laboratories) at baseline and 15, 30, 60, and 90 min after the intravenous administration of lidocaine (1 mg/kg), analyzing specimens from 12 apparently healthy volunteers and 40 patients with chronic viral hepatitis diagnosed by liver biopsy and serum tests. The patients were grouped on the basis of the histology activity index.