The impact of inter-laboratory glucose bias on the diagnosis of gestational diabetes mellitus: Comparison of common automated central laboratory methods.

BACKGROUND AND AIMS: The diagnosis of gestational diabetes mellitus (GDM) is based exclusively on glucose measurements, which are highly influenced by pre-analytical and analytical factors. Therefore, poor agreement across laboratories may affect the prevalence of GDM. We aimed to determine the inter-laboratory bias of glucose measurements and the impact on GDM prevalence. MATERIAL AND METHODS: A prospective cohort study of women (n = 110) referred for second-trimester GDM diagnostics using a 75 g oral glucose tolerance test. Maternal glucose was assessed from venous plasma at fasting, 1 h and 2 h. Venous blood were collected in Fluoride Citrate tubes and frozen. Samples were analyzed at five central laboratories using four different automated glucose Hexokinase methods and GDM prevalence was evaluated according to WHO2013 diagnostic criteria. RESULTS: Maximum inter-laboratory bias was 0.19, 0.30 and 0.27 mmol/L in fasting, 1 h and 2 h samples, respectively. GDM prevalence ranged 30.0-41.1% across laboratories. CONCLUSION: Inter-laboratory bias for mean venous glucose was low and within desirable limits. Nonetheless, the impact on GDM prevalence was considerable, which may inappropriately affect clinical practice.

First trimester serum matrix metalloproteinase-7 is a poor predictor of late-onset preeclampsia.

OBJECTIVES: This study aims to evaluate matrix metalloproteinase-7 as a first trimester biomarker for late-onset preeclampsia, both alone and in combination with mean arterial pressure, uterine artery pulsatility index, and maternal characteristics. STUDY DESIGN: We conducted a nested case-control study from a prospective cohort consisting of 416 pregnant women who attended a routine first trimester scan. Baseline variables were obtained at inclusion and analysed subsequently to formation of case and control groups. The study was designed to detect a mean difference of > 15% in matrix metalloproteinase-7 concentrations between groups with a statistical power of 80%. MAIN OUTCOME MEASURES: The primary outcome was preeclampsia with delivery after 34 weeks of pregnancy. RESULTS: The median matrix metalloproteinase-7 concentration in cases of late-onset preeclampsia (n = 27) was marginally lower compared to normotensive controls but this difference was not statistically significant. Matrix metalloproteinase-7 predicted 14.8% of cases at a 10% false-positive rate. Addition of matrix metalloproteinase-7 to any combination of variables did not significantly improve their performance. CONCLUSIONS: Matrix metalloproteinase-7 is not a useful biomarker for late-onset preeclampsia, neither alone nor in combination with mean arterial pressure, uterine artery pulsatility index, or maternal characteristics.