Abbott Architect Ci8200 Research Articles

Method modification to overcome interference by IGM paraproteins in the abbott architect CI8200 urate assay

Introduction In the Abbott urate assay, urate is oxidised to allantoin by uricase with production of hydrogen peroxide, which reacts to yield a quinoeimine dye read bichromatically at 548 and 700 nm. Three patients with IgM paraproteins (range 8.5-21.3 g/L) showed positive interference in this assay. Aims To investigate the interference by IgM, and to modify the assay to reduce or eliminate it. Methods Addition of solid sodium chloride to the reagent for the modified method (MM). Results Urate measurements by Abbott method (AM) on the three patients’ plasma samples (n = 3) have a mean of 0.60 mmol/L (range 0.50-0.77) and on the protein-free supernatants of these samples have a mean of 0.24 mmol/L (range 0.15-0.36). Removal of detectable levels of proteins using 20% TCA solution in these samples does not affect urate measurement. Patients’ samples (IgM paraprotein containing plasma, n = 3) measured by MM have a mean of 0.24 mmol/L (range 0.16-0.35). Control samples (no IgM paraprotein containing plasma, n = 3) measured by AM have a mean of 0.7 mmol/L (range 0.67-0.72) and measured by MM have a mean of 0.68 mmol/L (range 0.64-0.72). Discussion The urate measurements by the MM on patient samples with paraproteins correlate closely with urate measurements of protein-free supernatants of these samples. As for the controls, findings demonstrated modification of the reagent does not affect urate results in normal subjects.

Lipoprotein(a) levels and long-term cardiovascular risk in the contemporary era of statin therapy

Lipoprotein(a) [Lp(a)] has enhanced atherothrombotic properties. The ability of Lp(a) levels to predict adverse cardiovascular outcomes in patients undergoing coronary angiography has not been examined. The relationship between serum Lp(a) levels and both the extent of angiographic disease and 3-year incidence of major adverse cardiovascular events (MACE: death, myocardial infarction, stroke, and coronary revascularization) was investigated in 2,769 patients who underwent coronary angiography [median Lp(a) 16.4 mg/dl, elevated levels (≥30 mg/dl) in 38%]. An elevated Lp(a) was associated with a 2.3-fold [95% confidence interval (CI), 1.7-3.2, P < 0.001] greater likelihood of having a significant angiographic stenosis and 1.5-fold (95 CI, 1.3-1.7, P < 0.001) greater chance of three-vessel disease. Lp(a)≥30 mg/dl was associated with a greater rate of MACE (41.8 vs. 35.8%, P = 0.005), primarily due to a greater need for coronary revascularization (30.9 vs. 26.0%, P = 0.02). A relationship between Lp(a) levels and cardiovascular outcome was observed in patients with an LDL cholesterol (LDL-C) ≥70-100 mg/dl (P = 0.049) and >100 mg/dl (P = 0.02), but not <70 mg/dl (P = 0.77). Polymorphisms of Lp(a) were also associated with both plasma Lp(a) levels and coronary stenosis, but not a greater rate of MACE. Lp(a) levels correlate with the extent of obstructive disease and predict the need for coronary revascularization in subjects with suboptimal LDL-C control. This supports the need to intensify lipid management in patients with elevated Lp(a) levels.

Comparison of FT4 with log TSH on the Abbott Architect ci8200: Pediatric reference intervals for free thyroxine and thyroid-stimulating hormone

Background We evaluated the clinical validity of serum FT4 measurements by assessing its correlation with log TSH. To provide pediatric reference intervals (representative ranges) for FT4, and TSH on the Architect ci8200 integrated system. Methods This population-based study encompassed 6023 children (3369 females and 2654 males). The percentile and Hoffmann approaches for obtaining reference intervals on these analytes were also compared. Results FT4 correlation with log TSH was poor ( r = 0.010 for males and 0.050 for females). Reference intervals were established. TSH and FT4 did not show a significant sex difference; moreover, the intervals decreased with age for FT4 and TSH. Conclusions Whereas in a previous study ultrafiltration tandem mass spectrometry yielded a correlation of r = 0.90 for FT4 vs. log TSH this present study reveals a poor FT4 vs. log TSH correlation in the pediatric population studied and indicates the FT4 immunoassay conducted on the Abbott Architect ci8200 is less useful clinically than might have been expected. Reference intervals using the Hoffmann approach for pediatric in- and out-patients compare well with previously published results utilizing the percentile approach.

Comparison of immunoturbidimetric and immunonephelometric assays for specific proteins

Immunoturbidimetric assays for specific proteins are available on “open system” clinical chemistry analyzers. The analytical performance of nine immunoturbidimetric specific protein assays (C3, C4, CRP, Haptoglobin, IgA, IgG, IgM, RF, and Transferrin) was compared to immunonephelometry. Testing was performed on the Abbott ARCHITECT ci8200 and the Dade Behring BNII nephelometer and evaluated for precision, linearity, limit of detection, prozone phenomenon, method comparison, workflow, and proficiency testing survey comparison. Immunoturbidimetric assays performance was satisfactory for total precision, linearity, limit of detection and the prozone effect was not observed. Method comparison was acceptable for the immunoglobulins, CRP and transferrin but less favorable for the other assays, likely due to methodology and antibody specificity differences. Immunourbidimetric specific protein assays allow for efficient test consolidation on a general purpose clinical chemistry analyzer.

Short report: soluble transferrin receptor and depth of bone marrow suppression following high dose chemotherapy

Aim The transferrin receptor (TFR) mediates the transport of iron into cells. Circulating TFR can be measured as soluble transferrin receptor (sTfR) which has been shown to reflect erythropoietic activity in the bone marrow (Beguin 1992, Huebers et al 1990). We have sought to identify whether serial measurement of sTfR may predict depth or duration of bone marrow suppression in patients receiving high dose chemotherapy. We prospectively measured serial sTfR in nine consecutive patients with haematological malignancy admitted for various high dose regimens. Methods Samples for sTfR were collected from surplus patient specimens, centrifuged at 1000×g and frozen at -70°C, thawed and assayed as a batch following patient recovery. sTfR was measured by an automated turbidimetric method on an Abbott Architect ci8200 (Tina quant, Roche) that has been previously evaluated (Pfeiffer et al 2007). Haemoglobin and WCC were measured on Abbott Cell-Dyne 4000 analysers (Abbott Diagnostics). Results The sTfR nadir was associated with white cell nadir, and sTfR nadir and Day 5 sTfR were inversely associated with the number of red cell transfusions required. Conclusion Our preliminary data suggest that sTfR may be helpful in predicting the degree of bone marrow suppression in patients receiving intensive chemotherapy.

Evaluation of immunoturbidimetric specific protein methods using the Architect ci8200: comparison with immunonephelometry

Specific proteins have traditionally been analyzed using methodologies such as immunonephelometry on specialized analyzers. It is now possible to perform specific protein testing on clinical chemistry analyzers using immunoturbidimetry. Performance characteristics of turbidimetric assays for eight common specific proteins were evaluated against a nephelometric method. The Abbott Architect ci8200 and the Beckman Immage were used to perform IgA, IgG, IgM, C3, C4, haptoglobin, and transferrin testing. Abbott, Sentinel and Roche reagents were used to perform CRP testing on the ci8200. The specific protein assays were evaluated for precision, linearity, limit of detection, functional sensitivity, method comparison, prozone, and workflow. Total precision for the immunoturbidimetric assays was consistently better than 2% CV and linear throughout the dynamic range of the assays (recovery +/- 10% of target values). The limits of detection, functional sensitivities, and accuracy (as determined by performance against target values for proficiency testing samples and reference materials) are suitable for clinical purposes. Method comparison, as determined by correlation coefficients, and performance against proficiency testing samples, demonstrated good agreement between the turbidimetric and nephelometric tests. Both the turbidimetric and nephelometric assays provided reliable results under conditions of antigen excess. Specific protein test requests could be consolidated within our routine chemistry workload without impacting analytical test throughput. As demonstrated by their performance characteristics, the Architect ci8200 immunoturbidimetric specific protein assays are suitable for routine use and correlate well with representative immunonephelometric assays on the Beckman Immage analyzer. The ability to perform specific protein analyses on an integrated clinical chemistry/immunoassay system can allow for consolidation of testing on a single platform, resulting in improved laboratory operations efficiency.

Performance Characteristics of a Cystatin C Immunoassay with Avian Antibodies

Background: A new particle-enhanced turbidimetric immunoassay (PETIA) with avian antibodies for measuring serum/plasma cystatin C has been developed. The performance characteristics of the assay are described. Methods: Measurements were performed on a Roche Modular P and on an Abbott Architect ci8200 using Gentian cystatin C immunoassay. Results: Measuring range was 0.3–8.0 mg/L. Reference range was 0.57–1.09 mg/L. Total analysis time was 10 minutes. Linearity was absolute over the whole assay range. Recovery of samples and controls was within 98.6–109.4%. Total imparticle enhanced nephelometric cystatin C immunoassay (PENIA) by linear regression resulted in a slope within 0.97–1.02 and intercept within ±0.05 mg/L. Interference studies with drugs, anticoagulants, intralipid ( 11g/L), triglycerides ( 14 g/L) and bilirubin (420mg/L) antibodies, no interference with rheumatoid factor was observed. No carry-over was 6%) were both below 0.33 mg/L, which is less than the lowest standard. Sample stability was up to one month at 2–8°C. Stability of the reagents at 2–8°C was estimated to be 24 months.Stability of the reagents in use was minimum 9 weeks. Conclusions: Gentian cystatin C PETIA is shown to have excellent performance between methods. Interference results are improved due to avian antibodies and a broader span of the calibration curve. Avian antibodies are also known to have better immune response than mammalian antibodies towards mammalian antigens.

Pediatric Tube Direct Sampling by the Abbott Architect Integrated ci8200 Chemistry/Immunochemistry Analyzer

Handling and direct sampling from primary, barcode-labeled pediatric tubes is a challenge for laboratories processing substantial numbers of pediatric samples (1)(2). To prevent anemia as a result of frequent blood draws in pediatric patients, analyzers should be able to handle small sample volumes collected in pediatric tubes. However, most analyzers are developed for standard adult tubes and cannot handle primary pediatric tubes (1)(3). Pediatric samples therefore are often manually processed and transferred to sample cups (3); this process, however, is prone to errors and is time-consuming. In our study, we assessed the ability of the Abbott Architect ci8200 (Abbott Laboratories) to handle and directly sample from different types of primary, barcode-labeled pediatric lithium heparin gel tubes and determined the sample dead volumes of these tubes and the standard Abbott sample cup. Five types of tubes were tested: the Sarstedt Microvette® …