Analytical Performance and Quality Indicators of Fully Automated Immunoassays for sFlt-1 and PlGF.

Background: The ratio of the antiangiogenic factor, soluble fms-like tyrosine kinase 1 (sFlt-1), to the proangiogenic factor, placental growth factor (PlGF), is associated with increased risk of preeclampsia. Here, we describe an analytical evaluation of the Elecsys sFlt-1 and PlGF assays at the first North American site in which they were clinically implemented.

Methods: The analytical evaluation included short- and long-term imprecision, method comparison, accuracy, linearity, sample stability, limit of quantification verification, and measurement uncertainty.

Diagnostic implications of enumerating and reporting beta fraction(s) for the detection of beta-migrating monoclonal immunoglobulins in serum protein electrophoresis.

Background: Modern serum protein electrophoresis (SPE) resolves serum proteins in 6 major fractions, splitting beta (B) into beta1 (B1) and beta2 (B2). Beta-migrating monoclonal immunoglobulins (B-MC) commonly integrate into normal-looking peak shape(s) but may increase the fraction value, forming the basis for reflex testing. The objectives of this study were (1) to ascertain the value of beta fraction(s) reporting, and (2) to compare the diagnostic performance between different beta-flagging approaches, particularly ↑B versus ↑B1 and/or ↑B2.

Validating urinary measurement of beta-2-microglobulin with a Roche reagent kit designed for serum measurements.

Objective: To validate the use of a Roche serum beta-2-microglobulin (B2MG) kit for urinary B2MG measurements, and to establish reference limits for urinary B2MG/creatinine ratio from healthy individuals.

Design And Methods: The Roche B2MG Tina-Quant serum kit was used to measure urinary B2MG immunoturbidimetrically.

Results: Using human urine as a diluent, the B2MG method was linear from 73-2156 μg/L.