Nigel N. Brown

What is the most suitable blood collection tube for glucose estimation

Objectives Glucose is one of the most frequently measured analytes in laboratories. Most recent studies on glucose stabilities confirm that the sodium fluoride/potassium oxalate (NaF/KOx) tube is far from the gold standard. Citrate tubes have been suggested as the preferred tube type by many institutions. Greiner has introduced a glucose-specific tube (Glucomedics) containing NaF/KOx, citrate, and EDTA to minimise glycolysis. The aim was to determine which tube would be the most suitable for accurate glucose estimation in a routine laboratory setting. Design and methods The study process involved three experiments: (a) participant comparison using lithium heparin plasma as the comparative sample; (b) stability study (0, 1, 2 and 4 h); and (c) minimal fill volume for the citrate and the Glucomedics tubes. Results The patient comparison study of lithium heparin plasma showed that EDTA, NaF/KOx, and both citrate and Glucomedics if corrected for dilutional factors produced acceptable results. The stability study up to 4 h showed that the Glucomedics tube was most effective in preventing clinically significant change in glucose concentration at a room temperature. Both citrate and Glucomedics need to be filled within 0.5 mL of the recommended fill volume for acceptable results. Conclusion The Glucomedics tube is the most suitable for minimising glycolysis. Further improvements to it (use of correct dilutional factor and the addition of gel separator) would make this tube the benchmark for the most accurate estimation, best diagnosis and patient care decisions.

Which point-of-care creatinine analyser for radiology: direct comparison of the i-Stat and StatStrip creatinine methods with different sample types

Background Availability of whole blood creatinine estimation for patients scheduled to undergo radiological contrast investigations can provide information to aid patient care by reducing adverse effects and improving departmental efficiencies. Methods We performed imprecision studies, different patient sample type comparison in 40 participants, and a limited interference study with dopamine and dobutamine on the i-Stat and StatStrip point-of-care enzymatic analysers with the Beckman DxC800 Jaffe assay. Results Imprecision results showed that the i-Stat performed better. Patient comparison data indicated that the i-Stat provided better correlation than the StatStrip for all the different sample types with correlation coefficients (r2) being 0.995-0.996 and 0.918-0.995, respectively. The i-Stat results had a small positive bias of 6-9% for the three different sample types, which required different reference intervals. The StatStrip method showed greater scatter and overall small negative bias of 26% for the whole blood samples and a 10% positive bias with the plasma samples. Dopamine caused significant positive interference with the i-Stat only while dobutamine caused a small negative bias with the StatStrip method only. Conclusions The findings indicated there are differences offered by the two systems. The StatStrip requires a very small finger prick capillary sample, calculates estimation of the glomerular filtration rate and has an adjustment option to improve correlation with the local method. The i-Stat offers better analytical imprecision and patient comparison with the laboratory method with the three sample types but showed significant interference from dopamine. A final consideration was the availability of middleware to capture patient results with the i-Stat. Based on all the study data, the i-Stat was recommended.

Underappreciation of non-alcoholic fatty liver disease by primary care clinicians: limited awareness of surrogate markers of fibrosis

Non‐alcoholic fatty liver disease (NAFLD) is a common cause of incidental liver test abnormalities. General practitioners (GP) have a key role in identifying people with NAFLD at risk of significant liver disease. Recent specialist guidelines emphasise the use of fibrosis algorithms or serum biomarkers rather than routine liver tests, to assess advanced fibrosis.

Evaluation of the Greiner Bio-One serum separator BCA Fast Clot tube

Abstract Background: Current commercial tubes have difficulties in producing “true” serum from all blood samples even within the recommended clotting times. Hence, Becton Dickinson (BD) and now Greiner have produced tubes containing thrombin as the procoagulant to reduce the clotting time and increase the possibility of producing serum from anticoagulated blood samples. Methods: The Greiner BCA Fast Clot (GBBCAFC) tube was evaluated in a hospital environment using 40 participants, (30 healthy and 10 undergoing renal dialysis) for 32 analytes against the Greiner lithium heparin tube and the BD Rapid Serum Tubes (BD RST) tube measured on Beckman DxC 800 and DxI 800 analyzers. Clotting strength was also examined using thromboelastography (TEG). Results: The analytes results showed there was a very close agreement between the BD RST tube and GBBCAFC tube in comparison with lithium heparin plasma. The result comparison data showed equivalent performance with lower levels of hemolysis. The prolonged storage study also showed very similar agreement between the BD RST and the GBBCAFC tubes. Likewise, the TEG data showed there was very little difference in clotting ability between the tubes, and neither was capable of producing true serum from blood spiked with 2 U heparin/mL of blood. Conclusions: The study showed the GBBCAFC tube with the combination of the two procoagulants blood clotting activator and thrombin produced comparable performance with the lithium heparin plasma and the BD RST serum samples.

Evaluation of the accuracy of the Greiner Bio-One FC Mix Glucose tube.

*Corresponding author: Goce Dimeski, Pathology Queensland, Chemical Pathology, Princess Alexandra Hospital, Ipswich Road, Woolloongabba, Brisbane, QLD 4102, Australia, Phone: +61 7 3176 2290, Fax: +61 7 3176 7070, E-mail: goce_dimeski@health.qld.gov.au; and School of Medicine, University of Queensland, Brisbane, Queensland, Australia Kong S. Yow and Nigel N. Brown: Pathology Queensland, Chemical Pathology, Princess Alexandra Hospital, Brisbane, Queensland, Australia Letter to the Editor

Paraprotein interference with turbidimetric gentamicin assay

Introduction Gentamicin due to its low level of resistance and rapid bactericidal activity is commonly used to treat gram-negative bacteria. However, due to its toxic effects it needs to be monitored. To date, no interference has been reported with gentamicin assays. Materials and methods A patient with leg cellulitis and sepsis received a single dose of gentamicin and a sample was sent for gentamicin analysis. The sample showed high blank absorbance readings on Beckman DxC800 and DC800 analysers with various dilutions. A second sample was received and analysed on a Roche Cobas system to obtain a result. A third sample was received 107 hours later with the same results and this sample was then analysed neat and post ethanol precipitation on all the turbidimetric assays available on the DxC800 analyser. Results The high blank absorbance was observed upon addition of the reactive reagents due to protein precipitation. Although not obvious from the patient protein results, it was shown the presence of high IgM paraprotein, 18.9 g/L (reference range 0.4-2.3 g/L) was the cause of precipitation, giving high blank readings. Of all the other turbidimetric assays, only vancomicin and valproate showed similar high blank absorbance readings. To be able to provide more rapid results it was shown ethanol could be used as a precipitant of proteins in both calibrators and patient samples with acceptable recovery. Conclusion IgM paraprotein was identified as the cause of interference with the gentamicin, vancomicin and valproate assays. Protein interference in these assays can be overcome by precipitation with ethanol.

Digoxin overdose - an accurate method for determining free digoxin concentrations on general chemistry analysers post DigiFab treatment

To the Editor,A 58-year-old female presented post overdose of an unknown amount of digoxin 62.5 µg tablets. A level taken 6 h post ingestion was 10 µg/L (therapeutic range 0.8–2.0 µg/L). The patient was bradycardiac 36/min, and was administered five vials of DigiFab (DigiFab, Pherba, Sydney, NSW, Australia). Our digoxin method, Beckman Coulter on the DxC800 general chemistry ana-lyser (Beckman Coulter, Brea, CA, USA) is not suitable for digoxin estimation in the presence of DigiFab due to posi-tive interference.Digoxin continues to be prescribed for the treatment of cardiac disorders, most frequently atrial fibrillation [1]. Digoxin toxicity usually occurs in the context of renal impairment, but as in our case, can be due to deliberate overdose [2]. Additionally related compounds digitoxin, oleander, Chinese herbal medicines (Chan Su, Lu-Shen-wan), spironolactone, etc can contribute or independently produce digoxin toxicity [3]. It is estimated in the USA that 0.4% of all hospital admissions, 1.1% of outpatients and 10%–18% of nursing care residents suffer digoxin toxicity and this is on the decrease [2]. Digibind digoxin-specific antibodies or antidigoxin Fab fragments DigiFab (of ovine origin) are available for life threatening symptoms of severe toxicity. Recommendation for use of both antidotes is identical. Once these antidotes are administered it can be difficult to obtain accurate free digoxin concentrations on a large number of general chemistry or immunoassay analysers. McMillan et al. evaluated 13 methods designed to quantify free digoxin and reported 4/13 showed marked positive interference, 5/13 showed moderate and four methods showed minimal interference [4]. Removing the effect of digoxin Fab fragments can aid decisions regard-ing additional dosing, as well as determining the correct time to recommence digoxin therapy. Manufacturers method inserts indicate that routine methods are not suit -able for digoxin estimation when Digibind is used. Ultra-filtration of the sample to remove the Digibind or DigiFab is a method for eliminating interference. However, ultra-filtration methods are not standardised and may require matrix-specific calibrators and lengthen turn-around-times [4].Here we describe a protein precipitation method that will provide accurate free digoxin concentrations in the presence of the antidotes. Polyethylene glycol (PEG) is non-denaturing water soluble polymer that precipitates proteins [5]. This permits proteins and bound compounds to be removed, providing a supernatant of unbound com-pounds. To determine if this method is suitable for meas-uring free digoxin post DigiFab administration, samples were treated with PEG to remove the DigiFab and its bound digoxin, specifically to DigiFab. PEG concentration was 24 g/100 mL (Fluka#812160, polyethylene glycol 6000, Sigma Aldrich). Samples were mixed with equal volumes of the PEG solution (0.5 mL:0.5 mL), vortex mixed, than centrifuged (5 min, 3000

Multimorbidity and polypharmacy in diabetic patients with Nafld: Implications for disease severity and management

Abstract An observational study describing the number and type of chronic conditions and medications taken by diabetic patients with NAFLD and identifying characteristics that may impact liver disease severity or clinical management. Adults with type 2 diabetes have a high prevalence of nonalcoholic fatty liver disease (NAFLD) and increased risk of developing advanced liver disease. Appropriate management should consider the characteristics of the diabetic NAFLD population, as comorbid conditions and medications may increase the complexity of treatment strategies. Diabetic patients with NAFLD at risk of clinically significant liver disease (as assessed by the FIB-4 or NAFLD fibrosis scores) were recruited consecutively from the Endocrine clinic or primary care. Medical conditions, medication history, anthropometric measurements, and laboratory tests were obtained during assessment. NAFLD severity was classified by transient elastography and liver ultrasound into “no advanced disease” (LSM < 8.2 kPa) or “clinically significant liver disease” (LSM ≥ 8.2 kPa). The most common coexistent chronic conditions were metabolic syndrome (94%), self-reported “depression” (44%), ischaemic heart disease (32%), and obstructive sleep apnoea (32%). Polypharmacy or hyperpolypharmacy was present in 59% and 31% of patients respectively. Elevated LSM (≥ 8.2 kPa) suggesting significant liver disease was present in 37% of this at-risk cohort. Increasing obesity and abdominal girth were both independently associated with likelihood of having significant liver disease. There is a high burden of multimorbidity and polypharmacy in diabetic NAFLD patients, highlighting the importance of multidisciplinary management to address their complex health care needs and ensure optimal medical treatment.

Alcohol Consumption in Diabetic Patients with Nonalcoholic Fatty Liver Disease

Aim To examine the association between lifetime alcohol consumption and significant liver disease in type 2 diabetic patients with NAFLD. Methods A cross-sectional study assessing 151 patients with NAFLD at risk of clinically significant liver disease. NAFLD fibrosis severity was classified by transient elastography; liver stiffness measurements ≥8.2 kPa defined significant fibrosis. Lifetime drinking history classified patients into nondrinkers, light drinkers (always ≤20 g/day), and moderate drinkers (any period with intake >20 g/day). Result Compared with lifetime nondrinkers, light and moderate drinkers were more likely to be male (p = 0.008) and to be Caucasian (p = 0.007) and to have a history of cigarette smoking (p = 0.000), obstructive sleep apnea (p = 0.003), and self-reported depression (p = 0.003). Moderate drinkers required ≥3 hypoglycemic agents to maintain diabetic control (p = 0.041) and fibrate medication to lower blood triglyceride levels (p = 0.044). Compared to lifetime nondrinkers, light drinkers had 1.79 (95% CI: 0.67–4.82; p = 0.247) and moderate drinkers had 0.91 (95% CI: 0.27–3.10; p = 0.881) times the odds of having liver stiffness measurements ≥8.2 kPa (adjusted for age, gender, and body mass index). Conclusions In diabetic patients with NAFLD, light or moderate lifetime alcohol consumption was not significantly associated with liver fibrosis. The impact of lifetime alcohol intake on fibrosis progression and diabetic comorbidities, in particular obstructive sleep apnea and hypertriglyceridemia, requires further investigation.

Measurement of glycated hemoglobin in a patient with homozygous hemoglobin E

1 Pathology Queensland , Chemical PathologyPrincess Alexandra Hospital, Brisbane , Australia 2 School of Medicine , Southside Clinical School, The University of Queensland, Brisbane , Australia 3 Pathology Queensland , HaematologyPrincess Alexandra Hospital, Brisbane , Australia Keywords: HbA