Comparison of Procalcitonin Assays on KRYPTOR and LIAISON® XL Analyzers.

Our laboratory performs procalcitonin (PCT) assays on a Brahms KRYPTOR analyzer with the Brahms PCT sensitive Kryptor kit. In this study, we wanted to compare the assays obtained in this way with the ones performed on the LIAISON® XL. From January to May 2017, 171 samples were analyzed, of which 65 from female patients (age: 22-98 years) and 106 from male patients (age: 16-97 years). The PCT determination was performed using the LIAISON® XL and KRYPTOR analyzers, by chemiluminescence (Chemiluminescence immunoassay-CLIA) (LIAISON® BRAHMS PCT® II GEN) and immunofluorescence (Brahms PCT sensitive Kryptor) assay, respectively. For the LIAISON® BRAHMS PCT® II GEN, 52% of the results were placed between 0.0 and 0.5 ng/mL, 18% between 0.5 and 2.0 ng/mL, and 30% between 2.0 and 100 ng/mL; the mean was 4.09 ng/mL, the median 0.456 ng/mL, the maximum value 97.2 ng/mL, and the minimum value 0.02 ng/mL. For the Brahms PCT sensitive Kryptor, 55% of the results were positioned between 0.0 and 0.5 ng/mL, 21% between 0.5 and 2.0 ng/mL, and 24% between 2.0 and 100 ng/mL; the mean was 3.72 ng/mL, the median 0.39 ng/mL, the maximum value 103 ng/mL, and the minimum value 0.01 ng/mL. The mean of the results obtained with the two methods showed no significant differences (3.717 for Kryptor and 4.094 for LIAISON®). PCT assay with Brahms reagents, both on the Kryptor and LIAISON®XL platforms, offers excellent performance in terms of sensitivity and specificity.

Assessment of Access hsTnI 99th percentiles upper reference limits following IFCC recommendations.

BACKGROUND: The detection of an increase and/or decrease of cardiac troponin (cTnI) values, with at least one value above the 99th percentile of the upper reference limit (URL) have a central role in acute myocardial infarction (AMI) diagnosis. The employment of sex specific 99th percentile URLs and High-sensitivity (Hs) assays are recommended. We assessed sex specific 99th percentile URL for Access Hs-cTnI and AccuTnI3+ (Beckman Coulter) using European donor reference population following recent International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) recommendations. METHODS: 300 males and 300 females plasma samples were collected. Both chemiluminescent immunoenzymatic assays were performed on UniCel DxI 800 platform (Beckman Coulter). RESULTS: For Access hsTnI, the observed sex-specific 99th percentile URLs were 5.5 (90% CI: 4.4-7.6) for females and 13.9 ng/L (90% CI: 7.4-17.4) for males. For AccuTnI+3 we could not establish them because the assay couldn't report detectable values of troponin for most of the analyzed samples. CONCLUSION: The sex-specific 99th percentile URLs established for Access hsTnI assay were significantly lower than those declared by the manufacturer caused by the different choice of population selection, age groups and sample types: for those reasons, we maintain the 99th URLs provided by manufacturer.

A multicenter study for the evaluation of the reference interval for TSH in Italy (ELAS TSH Italian Study).

Background The aims of this study were: (1) to calculate reliable thyroid stimulating hormone (TSH) reference intervals using laboratory databases; (2) to evaluate the relationship between TSH, sex and age values in different large Italian populations. Methods The TSH values stored in the laboratory information system of clinical laboratories of four Italian city hospitals, including 146,801 TSH measurements (with the respective age and sex data of individuals) were taken in consideration. Assuming a log-normal distribution, to log-transformed TSH values were applied the Dixon's iterative principle in order to exclude the outliers. At the end of this iterative process 142,821 log-transformed TSH results remained. The four clinical laboratories measured serum TSH concentrations using the same TSH immunoassay method (Access TSH 3rd IS, using UniCel DxI platform). Results The TSH reference interval calculated in the present study (0.362-5.280 mIU/L) is similar to that suggested by the manufacturer for the Access TSH 3rd IS assay (0.45-5.33 mIU/L). TSH values in females were significantly higher than in males (females: mean=2.06 mIU/L; standard deviation [SD]=1.26 mIU/L; n=101,243; males: mean=1.92 mIU/L; SD=1.19 mIU/L; n=41,578; p<0.0001). Moreover, a negative linear relationship was observed between TSH throughout all interval age values (from 0 to 105 years). Conclusions The results of the present multicenter study confirm that data mining techniques can be used to calculate clinically useful reference intervals for TSH. From a pathophysiological point of view, our results suggest that some Northern populations of Italy might still suffer some harmful effects on the thyroid gland due to mild to moderate iodine intake deficiency. Specific clinical trials are needed to confirm these results.

The role of neutrophil gelatinase-associated lipocalin (NGAL) in cerebrospinal fluids for screening of acute bacterial meningitis.

BACKGROUND: Acute bacterial meningitis is a rare but extremely severe disease. The aim of this study was to investigate whether neutrophil gelatinase-associated lipocalin (NGAL) is present and measurable in cerebrospinal fluid (CSF) and if its assessment may be useful for identifying patients with bacterial meningitis. METHODS: Eligible specimens were all consecutive CSFs of patients with suspect acute bacterial meningitis that were referred from the Unit of Infectious Diseases for routine chemical and morphological analysis over a three months period. CSF measurements consisted in NGAL, glucose, and total protein concentrations, along with cell count and differential. RESULTS: Eighty eight CSFs were received throughout the study period, 58 (66%) with CSF findings compatible with bacterial meningitis. The values of white blood cells (WBC), polymorphonuclear (PMN) and mononuclear (MONO) leukocytes, red blood cells (RBC), total proteins, and NGAL were significantly increased in positive CSFs, whereas that of glucose did not significantly differ. A significant correlation was found between CSF concentration of NGAL and CSF values of PMN, WBC, RBC and total proteins, but not with that of glucose and MONO. The concentration of NGAL in CSF showed an area under the curve (AUC) of 0.94 for identifying positive CSFs, with specificity and sensitivity of 1.00 and 0.741 at a diagnostic threshold of 13 ng/mL. CONCLUSIONS: NGAL is present in CSF of patients with bacterial meningitis and its measurement may be helpful for identifying positive CSFs.

Evaluation of sample hemolysis in blood collected by S-Monovette using vacuum or aspiration mode.

BACKGROUND: In vitro hemolysis can be induced by several biological and technical sources, and may be worsened by forced aspiration of blood in vacuum tubes. This study was aimed to compare the probability of hemolysis by drawing blood with a commercial evacuated blood collection tube, and S-Monovette used either in the "vacuum" or "aspiration" mode. MATERIALS AND METHODS: The study population consisted in 20 healthy volunteers. A sample was drawn into 4.0 mL BD Vacutainer serum tube from a vein of one upper arm. Two other samples were drawn with a second venipuncture from a vein of the opposite arm, into 4.0 mL S-Monovette serum tubes, by both vacuum an aspiration modes. After separation, serum potassium, lactate dehydrogenase (LD) and hemolysis index (HI) were tested on Beckman Coulter DxC. RESULTS: In no case the HI exceed the limit of significant hemolysis. As compared with BD Vacutainer, no significant differences were observed for potassium and LD using S-Monovette with vacuum method. Significant increased values of both parameters were however found in serum collected into BD Vacutainer and S-Monovette by vacuum mode, compared to serum drawn by S-Monovette in aspiration mode. The mean potassium bias was 2.2% versus BD Vacutainer and 2.4% versus S-Monovette in vacuum mode, that of LD was 2.7% versus BD Vacutainer and 2.1% versus S-Monovette in vacuum mode. None of these variations exceeded the allowable total error. CONCLUSIONS: Although no significant macro-hemolysis was observed with any collection system, the less chance of producing micro-hemolysis by S-Monovette in aspiration mode suggest that this device may be used when a difficult venipuncture combined with the vacuum may increase the probability of spurious hemolysis.

Evaluation of the analytical performances of the novel Beckman Coulter AU5800.

OBJECTIVES: To assess the analytical performance of Beckman Coulter AU5800. DESIGN AND METHODS: Imprecision, linearity and comparison studies were performed on 12 routine clinical chemistry tests. RESULTS: Imprecision was comprised between 0.4 and 3.0%. The linearity was excellent, with regression coefficients always >1.000. The correlation with analogous tests on Unicell DxC ranged from 0.894 and 1.000. The productivity was 4884 tests/h. CONCLUSIONS: We found optimal balance between performance and productivity for the AU5800.

Relationship between sampling volume of primary serum tubes and spurious hemolysis.

BACKGROUND: We planned a study to establish whether spurious hemolysis may be present in low volume tubes or partially filled tubes. METHODS: Four serum tubes were collected in sequence from 20 healthy volunteers, i.e., 4.0 mL, 13 x 75 mm (discard tube), 6.0 mL, 13 x 100 mm half-filled, 4.0 mL, 13 x 75 mm full-draw and 6.0 mL, 13 x 100 mm full-draw. Serum was separated and immediately tested for hemolysis index (HI), potassium, aspartate aminotransferase (AST), and lactate dehydrogenase (LDH). RESULTS: The HI always remained below the limit of detection of the method (< 0.5 g/L) in all tubes. No statistically significant differences were recorded in any parameter except potassium, which increased by 0.10 mmol/L in 4 mL full-draw tubes. No clinically significant variation was however recorded in any tube. CONCLUSIONS: The results suggest that all types of tubes tested might be used interchangeably in term of risk of spurious hemolysis.

Influence of temperature and period of freezing on the generation of hemolysate and blood cell lysate.

BACKGROUND: There is little information on temperature and period of freezing for generating hemolysate and blood cell lysate. MATERIALS AND METHODS: Primary tubes containing whole blood were frozen at -20°C and -80°C and then serially thawed to assess cell lysis and clinical chemistry tests in centrifuged plasma. RESULTS AND CONCLUSIONS: Massive amount of blood cells lysis could only be obtained by storing samples 12h at -20°C, or 2h at -80°C.