What´s floating on my plasma?

We report on a preanalytical issue we encountered during routine clinical chemistry analyses, potentially leading to deviated analysis results and believe that it might help other laboratories to overcome similar problems. In a heparin-gel tube we measured an implausible glucose value of 0.06 mmol/L. Re-measurement of the same sample resulted in a glucose value of 5.4 mmol/L. After excluding an analytical error, we inspected the sample closer and found a white material as well as fatty droplets floating on the surface of the plasma tube. Evaluation of these structures revealed that the white particulate matter (WPM) consisted of fibrinogen, platelets and leukocytes and the fatty droplets most probably originated from the separator gel. We concluded that these structures formed a temporary clot in the instruments pipetting needle thereby altering the sampling volume and subsequently the measured glucose value. The formation of WPM might be attributable to high speed centrifugation, high cholesterol levels, the gel formulation or a combination of several issues such as temperature, heparin concentration, pH and patient-specific factors. The gel droplets were most probably caused by an aberrant gel formulation in combination with an improper storage of the empty tubes on the wards prior to phlebotomy. After adding an additional instrument cleansing cycle and changing to another batch of heparin tubes the problems could be significantly reduced

In-vitro hemolysis and its financial impact using different blood collection systems

Background: Hemolytic specimens are among the most challenging preanalytical issues in laboratory diagnostics. The type of blood collection tube in use is claimed to influence in vitro hemolysis. We aimed to examine this hypothesis and estimate the respective financial impact, evaluating routine blood samples from the past 4 years. Methods: A total of 47,820 hemolysis index (HI) values from five different time intervals (IV1-IV5) were compared against each other, representing the following tubes: IV1-Sarstedt Monovette; IV2-8 mL/16×100 mm Greiner BioOne (GBO) Vacuette; IV3/IV4-5 mL/16×100 mm GBO Vacuette; IV5-4.5 mL/13×75 mm GBO Vacuette. For estimation of the economic impact, material, personnel and analytical costs were calculated. Results: HI mean values in time interval IV2 were significantly higher than in all other intervals, while mean values amongst all other intervals were comparable. The number of moderately and severely hemolyzed samples increased with incrementing vacuum. Overall comparable costs between intervals IV1 and IV5 were €11,370, €14,045, €12,710, €11,213 and €8138 per 10,000 samples, respectively. Conclusions: Aspiration tubes and low vacuum tubes show comparable hemolysis rates. Increasing vacuum levels are associated with higher hemolysis rates. By decreasing in vitro hemolysis, financial savings up to €5907 per 10,000 samples could be gained

Changing the tide in vitamin D testing: An 8-year review of a demand management approach

Graphical abstract Highlights • Adding a mandatory accompanying information in the Vitamin D ordering process led to a significant reduction overall orders • Given that about one third of mandatory information was incorrect, we assume that the sheer obstacle is sufficient to reduce test numbers, regardless of its type or content • We estimated potential cost savings ranging from € 101,292 to € 516,704 for a four-year perio

Effectiveness of a laboratory gate-keeping strategy to overcome inappropriate test utilization for the diagnosis of heparin-induced thrombocytopenia

Effectiveness of a Laboratory Gate-Keeping Strategy to Overcome Inappropriate Test Utilization for the Diagnosis of Heparin-Induced Thrombocytopenia

Errors within the total laboratory testing process, from test selection to medical decision-making – A review of causes, consequences, surveillance and solutions

Laboratory analyses are crucial for diagnosis, follow-up and treatment decisions. Since mistakes in every step of the total testing process may potentially affect patient safety, a broad knowledge and systematic assessment of laboratory errors is essential for future improvement. In this review, we aim to discuss the types and frequencies of potential errors in the total testing process, quality management options, as well as tentative solutions for improvement. Unlike most currently available reviews on this topic, we also include errors in test-selection, reporting and interpretation/action of test results. We believe that laboratory specialists will need to refocus on many process steps belonging to the extra-analytical phases, intensifying collaborations with clinicians and supporting test selection and interpretation. This would hopefully lead to substantial improvements in these activities, but may also bring more value to the role of laboratory specialists within the health care setting

Influence of centrifugation conditions on the results of 77 routine clinical chemistry analytes using standard vacuum blood collection tubes and the new BD-Barricor tubes

Introduction: Although centrifugation is performed in almost every blood sample, recommendations on duration and g-force are heterogeneo-us and mostly based on expert opinions. In order to unify this step in a fully automated laboratory, we aimed to evaluate different centrifugation settings and their influence on the results of routine clinical chemistry analytes. Materials and methods: We collected blood from 41 healthy volunteers into BD Vacutainer PST II-heparin-gel- (LiHepGel), BD Vacutainer SST II-serum-, and BD Vacutainer Barricor heparin-tubes with a mechanical separator (LiHepBar). Tubes were centrifuged at 2000xg for 10 minutes and 3000xg for 7 and 5 minutes, respectively. Subsequently 60 and 21 clinical chemistry analytes were measured in plasma and serum samples, respec-tively, using a Roche COBAS instrument. Results: High sensitive Troponin T, pregnancy-associated plasma protein A, ß human chorionic gonadotropin and rheumatoid factor had to be excluded from statistical evaluation as many of the respective results were below the measuring range. Except of free haemoglobin (fHb) measure-ments, no analyte result was altered by the use of shorter centrifugation times at higher g-forces. Comparing LiHepBar to LiHepGel tubes at different centrifugation setting, we found higher lactate-dehydrogenase (LD) (P = 0.003 to < 0.001) and lower bicarbonate values (P = 0.049 to 0.008) in the lat ter. Conclusions: Serum and heparin samples may be centrifuged at higher speed (3000xg) for a shorter amount of time (5 minutes) without alteration of the analytes tested in this study. When using LiHepBar tubes for blood collection, a separate LD reference value might be needed

Heparin and citrate additive carryover during blood collection

Background Published evidence on the risk of additive carryover during phlebotomy remains elusive. We aimed to assess potential carryover of citrated and heparinized blood and the relative volume needed to bias clinical chemistry and coagulation tests. Methods We simulated standardized phlebotomies to quantify the risk of carryover of citrate and heparin additives in distilled water, using sodium and lithium as surrogates. We also investigated the effects of contamination of heparinized blood samples with increasing volumes of citrated blood and pure citrate on measurements of sodium, potassium, chloride, magnesium, total and ionized calcium and phosphate. Likewise, we studied the effects of contamination of citrated blood samples with increasing volumes of heparinized blood on heparin (anti-Xa) activity, lithium, activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT). We interpreted these results based on measurement deviations beyond analytical, biological and clinical significance. Results Standardized phlebotomy simulations revealed no significant differences in concentration of surrogate markers. Clinically significant alterations were observed after contamination of heparinized blood samples with volumes of citrated blood beyond 5-50 \u3bcL for ionized calcium and beyond 100-1000 \u3bcL for sodium, chloride and total calcium. Investigations of pure citrate carryover revealed similar results at somewhat lower volumes. Heparinized blood carryover showed clinically significant interference of coagulation testing at volumes beyond 5-100 \u3bcL. Conclusions Our results suggest that during a standardized phlebotomy, heparin or citrate contamination is highly unlikely. However, smaller volumes are sufficient to severely alter test results when deviating from phlebotomy guidelines