Sérothèque / Serum bank
Biochimiste, Dr ès Sciences
Spécialiste FAMH en chimie clinique
Dianalabs - Genève
Dr Reto Stricker
BACKGROUND: Cytomegalovirus (CMV) antibody donor screening assays have predominantly included both immunoglobulin G (IgG) and immunoglobulin M (IgM) detection. However, since in the majority of cases both CMV IgG and IgM are detected concomitantly during early seroconversion, CMV assays based only on IgG are now widely applied for donor screening. STUDY DESIGN AND METHODS: The performance of an automated microparticle CMV IgG assay (Abbott AxSYM CMV IgG microparticle enzyme immunoassay [MEIA]) was compared with an established total antibody blood screening assay (Abbott CMV Total AB EIA). Sensitivity and specificity were assessed using 5050 random blood donors and 13 seroconversion panels. A risk analysis was undertaken to estimate the residual risk of transfusion-transmitted CMV (TT-CMV) from presumptive seronegative blood components. RESULTS: The EIA achieved marginally (but not significantly) better resolved sensitivity (100%) than the AxSYM IgG assay (99.93%). The AxSYM IgG resolved specificity (99.34%) was superior to the EIA (96.4%). This superiority was maintained (98.61%) when a modified cutoff was applied to the AxSYM IgG assay to achieve 100 percent resolved sensitivity. The seroconversion sensitivities of the EIA and the AxSYM IgG were equivalent, detecting the same bleed as positive in the majority of the seroconversion panels tested. The median TT-CMV residual risk estimate for the two assays was approximately 1 in 66,000 (range, 42,000-165,000). CONCLUSION: The AxSYM IgG MEIA is suitable for blood donor screening and was optimized by applying a modified cutoff of 9 AU per mL. The modeling predicts that implementing the AxSYM IgG assay would not negatively impact the already very low risk of TT-CMV associated with seronegative blood components in Australia.
The ARCHITECT Toxo IgG and IgG Avidity assays have been developed as a fully automated panel for immune status determination and acute infection exclusion. Resolved relative specificity and sensitivity of the ARCHITECT Toxo IgG assay were 99.6% (1359/1365) and 99.7% (1096/1099) as determined on pregnant females, blood donor, and diagnostic specimens. Seroconversion sensitivity of the ARCHITECT assay was comparable with the AxSYM Toxo IgG assay. The ARCHITECT Toxo IgG Avidity assay detected 100.0% (124/124) of acute phase specimens (<4 months after infection) as low avidity, whereas the Vidas Toxo IgG Avidity assay detected 98.9% (89/90) as low avidity. In summary, the ARCHITECT Toxo IgG assay, using recombinant antigens, showed excellent specificity and sensitivity for acute phase as well as past infection specimens. The ARCHITECT Toxoplasmosis panel can be reliably used to rule out acute Toxoplasma gondii infection in pregnant women.
During a normal menstrual cycle, serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol, and progesterone can vary widely between cycles for the same woman, as well as between different woman. Reliable reference values based on the local population are important for correct interpretation of laboratory results. The purpose of our study was to determine detailed reference values for these hormones throughout the menstrual cycle using the Abbott ARCHITECT system. From 20 volunteers (age 20-36 years) with normal cycles and no use of oral contraceptives, samples were taken every day during their cycle. Volunteers received three vaginal ultrasound examinations (days 10 and 13, and 1 or 2 days after ovulation) to measure follicular and corpus luteum development. Hormone levels were measured using the corresponding ARCHITECT assay and were synchronized to the LH peak. Median, and 5th and 95th percentile values were determined for each day of the cycle, as well as for early follicular (days -15 to -6), late follicular (days -5 to -1), LH peak (day 0), early luteal (+1 to +4), mid-luteal (days +5 to +9), and late luteal (days +10 to +14) phases of the cycle. Based on our data, we were able to establish detailed reference values for LH, FSH, estradiol, and progesterone, which should aid in the interpretation of results for these reproductive hormones in a variety of circumstances.
OBJECTIVE: To assess the value of first trimester maternal serum free beta human chorionic gonadotropin (beta hCG), pregnancy-associated plasma protein (PAPP-A) concentrations and nuchal translucency (NT) as predictors of pregnancy complications. DESIGN: A retrospective collaborative study of beta hCG, PAPP-A and NT between 10 and 14 weeks of pregnancy in patients in whom pregnancy was followed to term. Nuchal translucency, maternal serum PAPP-A and free beta hCG concentrations were measured in 1779 women with singleton pregnancies and without aneuploidies. Individual values were expressed as multiple of medians (MoM). Normal and abnormal pregnancies were compared for these parameters. RESULTS: Irrespective of the presence or absence of pregnancy-associated pathologies; there was no change in the median MoM for NT. The median MoM for free beta hCG was significantly increased in women with threatened abortions whereas the median MoMs for PAPP-A in women with spontaneous abortions or with pre-term deliveries were decreased significantly compared to normal pregnancies. These parameters have however no clinical usefulness as determined by receiver operator characteristics curves. CONCLUSION: Since PAPP-A is a protease that specifically degrades insulin-like growth factor binding proteins we would conclude that the control of the insulin-like growth factor system in the first trimester of pregnancy might play a key role in determining subsequent pregnancy outcome.
- Biochemistry, chemistry, physics : Free medical journals
- Collection, storage, processing, and use of human biological samples: the spirit of the laws - Hachemi Ayad
- Prenatal screening and diagnosis : Guidelines, reviews