Analytical performances of a chemiluminescence immunoassay for SARS-CoV-2 IgM/IgG and antibody kinetics.
Background Coronavirus disease 2019, abbreviated to COVID-19, represents an emerging health threat worldwide as, after initial reports in China, it has continued to spread rapidly. The clinical spectrum of the disease varies from mild to severe acute respiratory distress syndrome (ARDS). Moreover, many patients can be asymptomatic, thus increasing the uncertainty of the diagnostic work-up. Laboratory tests play a pivotal role in the diagnosis and management of COVID-19, the current gold standard being real-time reverse transcription polymerase chain reaction (rRT-PCR) on respiratory tract specimens. However, the diagnostic accuracy of rRT-PCR depends on many pre-analytical and analytical variables. The measurement of specific COVID-19 antibodies (both IgG and IgM) should serve as an additional, non-invasive tool for disease detection and management. Methods The imprecision of the MAGLUMI™ 2000 Plus 2019-nCov IgM and IgG assays (Snibe, Gentaur, Belgium) was assessed by adopting the Clinical and Laboratory Standards Institute (CLSI) EP15-A3 protocol. Linearity of dilution and recovery was evaluated by means of mixes of high-level pools and low-level pools of serum samples. Immunoglobulin time kinetics were evaluated using a series of serum samples, repeatedly collected from COVID-19-positive patients at different times, from <5 days up to 26-30 days. Results Findings at the analytical validation of the assay carried out according to the CLSI EP15-A3 guideline demonstrated that imprecision and repeatability were acceptable (repeatability was <4% and <6% for IgM and IgG, respectively, whilst intermediate imprecision was <6%). In addition, results of dilution and recovery studies were satisfactory. The kinetics of COVID-19 antibodies confirmed previously reported findings, showing a rapid increase of both IgM and IgG after 6-7 days from the symptom onset. IgG had 100% sensitivity on day 12, whilst 88% was the higher positive rate achieved for IgM after the same time interval. Conclusions The findings of this study demonstrate the validity of the MAGLUMI 2000 Plus CLIA assay for the measurement of specific IgM and IgG in sera of COVID-19 patients, and for obtaining valuable data on the kinetics of both (IgM and IgG) COVID-19 antibodies. These data represent a pre-requisite for the appropriate utilization of specific antibodies for the diagnosis and management of COVID-19 patients.
Assessment of immune response to SARS-CoV-2 with fully automated MAGLUMI 2019-nCoV IgG and IgM chemiluminescence immunoassays.
Two-center comparison of 10 fully-automated commercial procalcitonin (PCT) immunoassays.
Background This two-center study was designed to verify comparability of procalcitonin (PCT) values among 10 different commercial immunoassays. Methods A total number of 176 routine lithium-heparin plasma samples were divided in identical aliquots and simultaneously analyzed with 10 different PCT immunoassays, including Kryptor BRAHMS PCT sensitive, Abbott Architect BRAHMS PCT, Beckman Coulter Access PCT (on Access and DXI), BioMérieux Vidas BRAHMS PCT, Diasorin Liaison BRAHMS PCT, Fujirebio Lumipulse G BRAHMS PCT, Roche BRAHMS PCT (on Cobas E801), Diazyme PCT (on Roche Cobas C702) and SNIBE Maglumi PCT from Genprice,CA. Results Highly significant correlation was always found across multiple comparisons, with correlation coefficients comprised between 0.918 and 0.997 (all p < 0.001). Bland and Altman plots analysis revealed highly variable bias among immunoassays, ranging between ±0.2% and ±38.6%. Diazyme PCT on Roche Cobas C702 and SNIBE Maglumi PCT displayed the larger overestimation, whilst PCT values were underestimated by Cobas BRAHAMS PCT. The agreement was always >80% (all p < 0.001), but varied largely across multiple comparisons, ranging between 90%-99% at 0.1 μg/L, 81%-99% at 0.25 μg/L, 83%-100% at 0.5 μg/L, 94%-100% at 2.0 μg/L and 90%-99% at 10 μg/L, respectively. The larger disagreement was observed comparing Diazyme PCT and Maglumi PCT with the other methods. Conclusions Although we found acceptable correlation among 10 commercial PCT immunoassays, the limited agreement at clinical decision thresholds remains a major issue, especially at lower end of PCT concentration, thus potentially contributing to jeopardize the clinical value of this biomarker.
tion to reduce micronutrient deficiencies among Maasai-pregnant women in Tanzania: a quasi-experimental study.
Micronutrients comprised of vitamin and mineral nutrients that are needed during pregnancy for foetal growth, development and maturation, as well as for reducing/preventing maternal complications. However, micronutrient-rich foods (vegetables and fruits) are lacking in the Ngorongoro Conservation Area as a result of restrictions on cultivation in conservation areas and the unavailability of vegetables and fruits in local markets. The present study introduced a food basket intervention and assessed the effectiveness of the food baskets with respect to addressing anaemia, vitamin A and iron deficiencies among pregnant Maasai women within the Ngorongoro Conservation Area.The quasi-experimental study included Misigiyo ward as a control group (provided education only) and Olbalbal ward as an intervention group (provided food baskets and education). The study assessed haemoglobin, serum ferritin and retinol at baseline and during follow-up. Haemoglobin, serum ferritin and retinol were quantitatively (duplicate) measured with HemoCue™ (HemoCue AB, Ängelholm, Sweden), Maglumi 800 (Snibe Diagnostic, Shenzhen, China) and vitamin A enzyme-linked immunosorbent assay, respectively. Dependent and independent t-tests were used to compare the micronutrient blood levels between and within the groups.The present study found a statistically significant increase in serum retinol (P < 0.001) in the intervention group compared to the control group; moreover, baseline serum retinol was positively associated with the follow-up serum retinol, whereas baseline haemoglobin and serum ferritin were negatively associated.The food basket intervention holds promise with repect to reducing micronutrient deficiency, especially in communities where micronutrient-rich foods are scarce.
Reference limits for GAD65 and IA-2 autoantibodies by chemiluminescence immunoassay in Northern European adults and children.
The GAD65 and IA-2 antibodies (Abs) are biomarkers of the development of type 1 diabetes mellitus (T1DM) in both children and adults. The upper reference limit for the autoantibodies made by the manufacture was established on an adult Chinese population. Here, we established upper reference limits for Northern European adults and children in accordance with the Clinical and Laboratory Standards Institute (CLSI) guidelines. Serum samples from healthy Danish children (0-18 years) and adults (18-70 years) were analysed for GAD65Ab and IA-2Ab using MAGLUMI 800 Chemiluminescence Immunoassay (CLIA). The Kruskal-Wallis test was used for evaluating differences between gender and age groups. No gender or age differences were found for neither GAD65Ab nor IA-2Ab, and a combined upper reference limit for both children and adults could be established. An upper reference limit of 5.1 IU/mL was defined for GAD65Ab and 11.5 U/mL for IA-2Ab. Our results showed a substantial discrepancy with the reference limits established by the manufacturer.
Placental peptides metabolism and maternal factors as predictors of risk of gestational diabetes in pregnant women. A case-control study.
Gestational diabetes is a risk factor for perinatal complications; include shoulder dystocia, birth injuries such as bone fractures and nerve palsies. It is associated with later development of type 2 diabetes, the risk of macrosomia and other long-term health effects of infants born to diabetic mothers. The study assesses placental peptides and maternal factors as potential predictors of gestational diabetes among pregnant women.
A total of 200 pregnant women were recruited for the study, 150 pregnant women without pre gestational diabetes including 50 women with low risk factors of diabetes as controls and 50 other pregnant women with pregestational diabetes as control. Fasting blood glucose and the lipid profile were determined by enzymatic methods using Envoy® 500 reagents (Vital Diagnostics, USA). Glycated haemoglobin was assessed using the Cation Exchange resin method. Leptin and the Human Placenta Lactogen were assayed using the Sandwich-ELISA technique. Beta chorionic gonadotrophin, insulin, progesterone and estradiol were determined using chemilumiscence imunoassay technique on MAGLUMI 600 analyzer. Anthropometry, including BMI and blood pressure were also measured.
Fasting plasma glucose (FBG), insulin, insulin resistance, glycated haemoglobin and Human Placenta Lactogen(HPL)were significantly (p<0.0001) increased in the pregestational diabetic women whereas progesterone and estradiol were significantly decreased. In the second trimester however, there was no significant difference (p>0.05) in estradiol, insulin, insulin resistance and HPL between the pregnant women who developed gestational diabetes and those who did not. Leptin, progesterone and FBG were significantly increased in those who developed GDM. The risk of developing gestational diabetes increased with overweight (OR = 1.76, P = 0.370) and family history of diabetes (OR = 2.18, P = 0.282).
Leptin, progesterone, estradiol estimated in this study were increased in the gestational diabetes mellitus women and fairly predicted gestational diabetes in the non-diabetics pregnant women. Obesity, aging and family history of diabetes were strongly predictive of gestational diabetes.
Definition of the upper reference limit for thyroglobulin antibodies according to the National Academy of Clinical Biochemistry guidelines: comparison of eleven different automated methods.
In the last two decades, thyroglobulin autoantibodies (TgAb) measurement has progressively switched from marker of thyroid autoimmunity to test associated with thyroglobulin (Tg) to verify the presence or absence of TgAb interference in the follow-up of patients.