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  • Author: Fatma Meriç Yılmaz x
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Abstract

Objective:

Automated urine analysis is usually preferred for laboratories with intensive workload. The aim of this study was to evaluate the performance of the automated urine analyser H-800/FUS-100 and detect the error sources.

Materials and methods:

One thousand four hundred fifty nine fresh urine samples were analyzed with H-800/FUS-100 automated systems. The urine sediment of the samples with discrepant strip and microscopy results were confirmed by manual microscopy. Precision and carry over studies were performed.

Results:

The discrepancy is detected in a ratio of 5.89% between chemical analysis (H-800) and microscopic analysis (FUS-100) of the device. A total of 86 discrepant samples were detected. Fifty six of 86 were erythrocyte discrepancies (65.1%) and 30 of 86 were leukocyte discrepancies (34.9%). The results of carry over analysis for erythrocyte and leukocyte were 21.85% and 13.64%, respectively.

Conclusions:

Sixteen (1.09%) of 1459 patients’ results in FUS-100 were discrepant with manual microscopy. Commonly, yeasts and crystals affected erythrocyte counts and calcium oxalate and amorphous crystals affected the leukocyte counts. Images should be reviewed for every sample when automated systems are used for urine analysis. Especially if discrepancy is detected between chemical and microscobic analysis, the results should also be confirmed with manual microscopy.

Abstract

Background

As vitamin D has recently been implicated in various diseases, vitamin D testing has gained a lot more significance. Vitamin D deficiency is quite prevalent, and detection of this condition is important. Several manufacturers have developed new automated immunoassays for this purpose. In this study, we aimed to evaluate the analytical performance of the Access Total 25(OH) Vitamin D immunoassay on the Beckman Coulter Unicel DXI 800 analyzer, through comparison with the reference method, liquid chromatography/tandem mass spectrometry (LC-MS/MS).

Methods

The study was conducted with 148 patient samples which were sent to Ankara Numune Training and Research Hospital for routine vitamin D testing. Every sample was analyzed with both Unicel DXI 800 immunoassay analyzer and LC-MS/MS. The concordance of the results was evaluated with Passing-Bablok regression analysis and Bland-Altman plot. Additionally, imprecision, interference, limit of blank (LOB), recovery, linearity and carry-over studies were performed for the Beckman Coulter Unicel DXI 800 analyzer.

Results

When compared to LC-MS/MS, the Access Total 25(OH) Vitamin D immunoassay on the Beckman Coulter Unicel DXI 800 analyzer had an R-value of 0.957 (intercept: −3.938, slope: 1.185) and a mean bias of 9.5%. The concordance correlation coefficient (CCC) between the two methods was 0.916. The intra-assay, inter-assay and total coefficient of variation (CV%) for the Unicel DXI 800 vitamin D immunoassay were 3.3%, 5.3% and 8.3%, respectively, at 31.7 ng/mL concentration, and 2.1%, 3.2% and 7%, respectively, at 66.8 ng/mL concentration.

Conclusions

The Access Total 25(OH) Vitamin D immunoassay method has acceptable analytical performance, and the results are in concordance with the LC-MS/MS results.

Abstract

Background: Validation of blood collection tubes are important to determine the role of different collection tubes which influence the assurance of laboratory results. We compared two different tubes (Improvacuter and Becton Dickinson [BD] Vacutainer) and investigated the effect of gel and storage time in comparison with each other.

Methods: We compared the results of nine immunoassays performed on UniCel® DxI 800 using blood samples collected in BD Vacutainer SST II Advance tubes, Improvacuter Gel and Clot Activator tubes, BD Vacutainer Clot Activator tubes and Improvacuter tubes. Analytes were measured in all tubes on 3 consecutive days to study the effect of long-term storage. Evaluation of clinical significance was performed based on total allowable error.

Results: Estradiol and testosterone concentrations obtained from Improvacuter Gel and Clot Activator tubes and BD Vacutainer SST II Advance tubes remained below the lower limits of analytical range for the same analytes while they were within the limits in BD Vacutainer Clot Activator tubes and Improvacuter tubes. Statistical significance of stability was not clinically significant for the hormone parameters we tested in all four tubes.

Conclusions: Gel containing tubes (both BD and Improve) gave comparable results with the tubes which do not contain gel except for estradiol and testosterone. The use of gel containing tubes for estradiol and testosterone are not recommended on UniCel® DxI 800 according to our results. The change in the analyte concentrations over 48 h remained within the TEA limits for the studied analytes. Improve tubes gave similar results to BD tubes.

Abstract

Objective:

Macroprolactinemia detection is important to avoid unneccessary tests and overtreatment. High prolactin levels require routine screening and clinicians must be aware of macroprolactinemia frequency encountered with the method in use. In this study we aimed to determine the macroprolactinemia rate in our laboratory.

Methods:

Prolactin results of different patients analysed on two different immunoassay systems within two consecutive years were evaluated. Analyses were performed on Beckman Coulter UniCel® DxI800 and Roche Cobas® e601 immunoassay systems. Samples for macroprolactin analysis were precipitated using polyethylene glycol (PEG) 6000. Post-PEG recovery <40% was defined as positive, 40–60% as gray-zone and >60% as negative for macroprolactin.

Results:

For the samples analysed on DxI800 (n=14,958) hyperprolactinemia frequency was 8.1% (n=1208). One of 138 samples submitted for macroprolactin analysis was positive, while three of them were in the gray-zone. For the samples analysed on Cobas® e601 (n=14,040) hyperprolactinemia frequency was 13.9% (n=1954). Eighteen of 238 samples submitted for macroprolactin analysis were positive, while 21 of them were in the gray-zone.

Conclusion:

A difference was found between two immunoassay systems used in our laboratory in terms of macroprolactinemia rate. However, inability of simultaneous analyses on both systems, lack of evaluation with gel filtration chromatography, and heterophile antibody blocking tube were the limitations.

Abstract

Objective

Hemoglobinopathies are a common public health problem in Turkey. In the screening of these disorders in population, cation-exchange high performance liquid chromatography (HPLC) is accepted as the gold standard method. In this study, the aim was to assess four different HPLC devices used in hemoglobinopathy screening.

Materials and methods

A total of 58 blood samples were analyzed with four different HPLC methods (Bio-Rad variant II, Agilent 1100, Tosoh G8 and Trinity Ultra2 trademarks).

Results

The comparison study demonstrated a good correlation between the results of each HPLC analyzer and the reference value obtained by averaging all the HbA2 results belonging to the methods tested in the study [ (Tosoh G8 (r=0.988), Bio-Rad variant II (r=0.993), Agilent 1100 (r=0.98) and Trinity Ultra2 (r=0.992) ]. HbA2 determination in the presence of HbE was interfered in both Bio-Rad variant II and Tosoh G8.

Conclusion

The analyzers were found to have compatible HbA2 results but with accompanying different degrees of proportional and systematic biases. HPLC analyzers may be affected by different hemoglobin variants at different HbA2 concentrations, which is an important point to take into consideration during the evaluation of HbA2 results in thalassemia screening.

Abstract

Objective: Our aim was to determine whether cystatin C level has a superiority to creatinine to assess kidney functions in rapid decreases of glomerular filtration rate due to acute mercury exposure in children. Eight different glomerular filtration rate calculation formulas which have been used creatinine and/or cystatin C were also compared.

Methods: Serum urea, creatinine and cystatin C values of 39 mercury exposed children were measured. Glomerular filtration rates were calculated by eight different formulas. Patient group was divided into three subgroups according to mercury levels.

Results: Cystatin C and mercury levels of the patients were found significantly different from control group (p<0.001). There was not a significant difference in creatinine and urea values between two groups (p=0.913, p=0.236). There was not a significant difference between patient and control groups in GFR calculations which have been used serum creatinine and height or which have been used urea additional to them (p=0.069, p=0.559, p=0.424, p=0.945, respectively), but there was a significant difference between patient and control groups in GFR calculations which have been used cystatin C only or creatinine, urea and height in addition to this (p<0.001, p<0.001, p=0.042, p<0.001, respectively). In sugroup analysis, cystatin C results and the results of three GFR calculations of four GFR calculations which were used cystatin C were found different in control group according to subgroups but there was not a difference between subgroups.

Conclusion: Cystatin C level is a better indicator than creatinine to assess kidney functions in rapid decreases of glomerular filtration rate due to acute exposure of mercury. Formulas using cystatin C gave better results than formulas using creatinine and height in estimation of glomerular filtration rate.