We describe an unusual case of a primary evacuated blood collection tube with floating separator gel, which has been collected from a 50-year-old man submitted to a percutaneous coronary intervention (PCI). The sample was collected from the femoral artery in a primary evacuated blood collection tube containing lithium-heparin. After centrifugation of the specimen, an unusual positioning of the separator gel was observed, which migrated at the topmost layer, whereas the packed blood cells remained in the middle and the plasma at the bottom. The potential interfering substance was found to be a contrast dye, 140 ml of which were administered to the patient during a revascularization procedure for acute myocardial infarction. The potential aspiration of the gel inappropriately positioned at the top of the tube by laboratory instrumentation can produce several technical and clinical problems, when not reliably detected. First, the needle of the instrument might be partially or completely obstructed by the gel, thus jeopardizing the integrity and correct functioning of the instrument. The aspiration of gel along with the sample matrix might also spuriously modify the test results, since an inappropriate amount of serum or plasma would be analyzed.

The MCE is characterized by a high throughput and it seems a suitable approach for laboratory monitoring of alcohol abuse when CDT is used as medical parameter in the diagnosis and follow-up of heavy drinking. However, CDT measured by screening techniques must be confirmed by a confirmatory technique, in particular for forensic purpose.

Introduction: Measurement and monitoring of blood glucose levels in hospitalized patients with portable glucose meters (PGMs) is performed widely and is an essential part of diabetes monitoring, despite the increasing evidence of several interferences which can negatively bias the accuracy of measurements. The purpose of this study was to evaluate the eff ect of the hematocrit on the analytical performances of diff erent PGMs as compared with a reference laboratory assay. Materials and methods:The eff ect of various hematocrit values (~0.20, ~0.45 and ~0.63 L/L) were assessed in three whole blood specimens with diff erent glucose concentration (~1.1, ~13.3, and ~25 mmol/L) by using six diff erent commercial PGMs. The identical samples were also tested with the laboratory reference assay (i.e., hexokinase). The percentage diff erence from the laboratory assay (%Diff ) was calculated as follows: % Diff = average PGM value -value from laboratory assay x 100 / value from laboratory assay. Results: The %Diff of the six diff erent PGMs were rather broad, and comprised between 56.5% and -34.8% in the sample with low glucose concentration (~1.1 mmol/L), between 40% and -32% in the sample with high glucose concentration (~13.3 mmol/L), and between -50% and 15% in the sample with very high glucose concentration (~25 mmol/L), respectively. It is also noteworthy that a very high hematocrit value (up to 0.63 L/L) generated a remarkable negative bias in blood glucose (-35%) as measured with the laboratory assay, when compared with the reference sample (hematocrit 0.45 L/L). Conclusion:The results of this analytical evaluation clearly confi rm that hematocrit produces a strong and almost unpredictable bias on PGMs performances, which is mainly dependent on the diff erent type of devices. As such, the healthcare staff and the patients must be aware of this limitation, especially in the presence of extreme hematocrit levels, when plasma glucose assessment with the reference laboratory technique might be advisable.

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