Cross-reactivity of insulin analogues with three insulin assays.

Background: Immunometric assays have recently shown higher specificity in the detection of human insulin than radioimmunoassays with almost no cross-reaction with proinsulin or C peptide. The introduction of the new insulin analogues on the market, however, has raised the need to define their cross-reactivity in these assays. Several studies have been published in this regard with different results.

Serum vitamin B12 levels during the first trimester of pregnancy correlate with newborn screening markers of vitamin B12 deficiency.

Introduction: Low maternal vitamin B12 status is a risk factor for various adverse pregnancy outcomes. Although vitamin B12 deficiency is not a primary target of newborn screening (NBS) programs, measurements of propionylcarnitine (C3) and its ratios with acetylcarnitine (C3/C2) and palmitoylcarnitine (C3/C16) may incidentally identify vitamin B12-deficient newborns. The objective of this study was to measure vitamin B12 levels in women during the first trimester of pregnancy, evaluate predictors of these concentrations, and study their relationship with newborn screening results.