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Blood gas analyzers can be alternatives to laboratory autoanalyzers for obtaining test results in just a few minutes. We aimed to find out whether the results from blood gas analyzers are reliable when compared to results of core laboratory autoanalyzers. This retrospective, single-centered study examined the electronic records of patients admitted to the emergency department of a tertiary care teaching hospital between May 2014 and December 2017. Excluded from the study were patients under 18 years old, those lacking data, those who had any treatment before the laboratory tests, those whose venous gas results were reported more than 30 minutes after the blood sample was taken and for whom any of the laboratory tests were performed at a different time, and recurrent laboratory results from a single patient. Laboratory results were analyzed from a total of 31,060 patients. The correlation coefficients for sodium, potassium, hemoglobin, hematocrit, and glucose levels measured by a blood gas analyzer and a laboratory autoanalyzer were 0.725, 0.593, 0.982, 0.958, and 0.984, respectively; however, there were no good, acceptable agreement limits for any of the parameters. In addition, these results did not change according to the different pH stages (acidosis, normal pH and alkalosis). The two types of measurements showed a moderate correlation for sodium and potassium levels and a strong correlation for glucose, hemoglobin, and hematocrit levels, but none of the levels had acceptable agreement limits. Clinicians should be aware of the limitations of blood gas analyzer results.

Abstract Background Microscopic evaluation of urine is inconsistently performed in veterinary clinics. The IDEXX SediVue Dx® Urine Sediment Analyzer (SediVue) recently was introduced for automated analysis of canine and feline urine and may facilitate performance of urinalyses in practice. Objective Compare the performance of the SediVue with manual microscopy for detecting clinically relevant numbers of cells and 2 crystal types. Samples Five-hundred thirty urine samples (82% canine, 18% feline). Methods For SediVue analysis (software versions [SW] 1.0.0.0 and 1.0.1.3), uncentrifuged urine was pipetted into a cartridge. Images were captured and processed using a convolutional neural network algorithm. For manual microscopy, urine was centrifuged to obtain sediment. To determine sensitivity and specificity of the SediVue compared with manual microscopy, thresholds were set at ≥5/high power field (hpf) for red blood cells (RBC) and white blood cells (WBC) and ≥1/hpf for squamous epithelial cells (sqEPI), non-squamous epithelial cells (nsEPI), struvite crystals (STR), and calcium oxalate dihydrate crystals (CaOx Di). Results The sensitivity of the SediVue (SW1.0.1.3) was 85%-90% for the detection of RBC, WBC, and STR; 75% for CaOx Di; 71% for nsEPI; and 33% for sqEPI. Specificity was 99% for sqEPI and CaOx Di; 87%-90% for RBC, WBC, and nsEPI; and 84% for STR. Compared to SW1.0.0.0, SW1.0.1.3 had increased sensitivity but decreased specificity. Performance was similar for canine versus feline and fresh versus stored urine samples. Conclusions and Clinical Importance The SediVue exhibits good agreement with manual microscopy for the detection of most formed elements evaluated, but improvement is needed for epithelial cells.

Glial fibrillary acidic protein (GFAP) is a biomarker candidate indicative of intracerebral hemorrhage (ICH) in patients with symptoms of acute stroke. GFAP is released rapidly in the presence of expanding intracerebral bleeding, whereas a more gradual release occurs in ischemic stroke. In this study the diagnostic accuracy of plasma GFAP was determined in a prospective multicenter approach. Within a 1-year recruitment period, patients suspected of having acute (symptom onset<4.5 h before admission) hemispheric stroke were prospectively included into the study in 14 stroke centers in Germany and Switzerland. A blood sample was collected at admission, and plasma GFAP was measured by use of an electrochemiluminometric immunoassay. The final diagnosis, established at hospital discharge, was classified as ICH, ischemic stroke, or stroke mimic. The study included 205 patients (39 ICH, 163 ischemic stroke, 3 stroke mimic). GFAP concentrations were increased in patients with ICH compared with patients with ischemic stroke [median (interquartile range) 1.91 μg/L (0.41-17.66) vs 0.08 μg/L (0.02-0.14), P<0.001]. Diagnostic accuracy of GFAP for differentiating ICH from ischemic stroke and stroke mimic was high [area under the curve 0.915 (95% CI 0.847-0.982), P<0.001]. A GFAP cutoff of 0.29 μg/L provided diagnostic sensitivity of 84.2% and diagnostic specificity of 96.3% for differentiating ICH from ischemic stroke and stroke mimic. Plasma GFAP analysis performed within 4.5 h of symptom onset can differentiate ICH and ischemic stroke. Studies are needed to evaluate a GFAP point-of-care system that may help optimize the prehospital triage and management of patients with symptoms of acute stroke.

Reliable automated blood cell characterization and quantification remain challenging in pathologic samples, whereas slide reviews due to unnecessary flagging should be avoided. We compared 4 modern hematology analyzers—Abbott Sapphire, Siemens Advia 120, Sysmex XE-2100, and Beckman Coulter DxH 800—regarding complete blood cell count (CBC), leukocyte differential count, and flagging efficacy in a total of 202 samples from hematology patients and normal controls. Manual differential count was used as reference. The analyzers exhibited very good correlation for CBC parameters. Neutrophils and eosinophils also showed very good correlations, whereas lymphocytes and monocytes correlated fairly. The Advia 120 displayed notably lower measurements for both parameters, which is attributable to classification of some events as large unstained cells. Basophil counts were unreliable with all analyzers. Flagging for blasts and immature granulocytes showed moderate sensitivity and specificity. Operators must not rely on blast flagging alone to detect leukemic samples with any analyzer.

Background. Pseudothrombocytopenia is a spurious thrombocytopenia caused mostly by ethylenediaminetetraacetic acid (EDTA) use, and if detected early, unnecessary testing and treatment can be avoided. We present pseudothrombocytopenia caused by EDTA and citrate in an asymptomatic healthy child, as well as the value of using peripheral blood smear, platelet histogram, and flag data. Case. A previously healthy 13-year-old girl with thrombocytopenia who developed tonsillitis 12 days previously was referred to our hematology department. Laboratory tests revealed severe thrombocytopenia (17x103/µL) in EDTA samples. A peripheral blood smear revealed numerous platelet clumping. We hypothesized EDTA-dependent pseudothrombocytopenia and ordered a platelet count by citrate tube. A citrate tube revealed thrombocytopenia with a platelet count of 55x103/µL. The platelet count (175x103/µL) returned to normal with heparin tubing. All blood samples had a similar platelet histogram and flags in the autoanalyzer. The platelet histogram indicated a serrated/sawtooth curve containing the largest platelet aggregates. Platelet flags alert messages about platelet clumping. Conclusions. Peripheral blood smear is the most reliable test for pseudothrombocytopenia. If the physician has no experience with smear examination, both laboratory technician and physician should be aware of abnormal platelet histograms and platelet clumping messages in platelet flags, which indicate pseudothrombocytopenia.

The calibrated automated thrombogram (CAT) assay in plasma is a versatile tool to investigate patients with hypo- or hypercoagulable phenotypes. The objective was to make this method applicable for whole blood measurements. Thin-layer technology and the use of a rhodamine 110-based thrombin substrate appear to be essential for a reliable thrombin generation (TG) assay in whole blood. Using this knowledge we developed a whole blood CAT-based assay. We demonstrated that the whole blood CAT-based assay is a sensitive and rapid screening test to assess function of the hemostatic system under more nearly physiological conditions than the TG assay in plasma. Under conditions of low tissue factor concentration (0.5 pmol/L) and 50% diluted blood, the intraassay CV of the thrombogram parameters, endogenous thrombin potential and thrombin peak height, were 6.7% and 6.5%, respectively. The respective interassay CVs were 12% and 11%. The mean interindividual variation (SD) of 40 healthy volunteers was 633 (146) nmol · min/L for the endogenous thrombin potential and 128 (23) nmol/L for the thrombin peak. Surprisingly, erythrocytes contributed more than platelets to the procoagulant blood cell membranes necessary for optimal TG. Statistically significant (P < 0.001) and potentially clinically significant correlations were observed between circulating factor-VIII concentrations in blood of hemophilia A patients and endogenous thrombin potential (r = 0.62) and thrombin peak height (r = 0.58). We have developed a reliable method to measure TG in whole blood. The assay can be performed with a drop of blood and may provide a useful measurement of TG under more physiological conditions than plasma.

Meningitis caused by Mycobacterium tuberculosis is a major cause of morbidity and mortality worldwide. We evaluated the performance of cerebrospinal fluid (CSF) testing with the GeneXpert MTB/RIF assay versus traditional approaches for diagnosing tuberculosis meningitis (TBM). Patients were adults (n = 37) presenting with suspected TBM to the Hospital Nacional Dos de Mayo, Lima, Peru, during 12 months until 1st January 2015. Each participant had a single CSF specimen that was divided into aliquots that were concurrently tested for M. tuberculosis using GeneXpert, Ziehl-Neelsen smear and culture on solid and liquid media. Drug susceptibility testing used Mycobacteria Growth Indicator Tube (MGIT 960) and the proportions method. 81% (30/37) of patients received a final clinical diagnosis of TBM, of whom 63% (19/30, 95% confidence intervals, CI: 44-80%) were HIV-positive. 22% (8/37, 95%CI: 9.8-38%), of patients had definite TBM. Because definite TBM was defined by positivity in any laboratory test, all laboratory tests had 100% specificity. Considering the 30 patients who had a clinical diagnosis of TBM: diagnostic sensitivity was 23% (7/30, 95%CI: 9.9-42%) for GeneXpert and was the same for all culture results combined; considerably greater than 7% (2/30, 95%CI: 0.82-22%) for microscopy; whereas all laboratory tests had poor negative predictive values (20-23%). Considering only the 8 patients with definite TBM: diagnostic sensitivity was 88% (7/8, 95%CI: 47-100%) for GeneXpert; 75% (6/8, 95%CI: 35-97%) for MGIT culture or LJ culture; 50% (4/8, 95%CI 16-84) for Ogawa culture and 25% (2/8, 95%CI: 3.2-65%) for microscopy. GeneXpert and microscopy provided same-day results, whereas culture took 20-56 days. GeneXpert provided same-day rifampicin-susceptibility results, whereas culture-based testing took 32-71 days. 38% (3/8, 95%CI: 8.5-76%) of patients with definite TBM with data had evidence of drug-resistant TB, but 73% (22/30) of all clinically diagnosed TBM (definite, probable, and possible TBM) had no drug-susceptibility results available. Compared with traditional culture-based methods of CSF testing, GeneXpert had similar yield and faster results for both the detection of M. tuberculosis and drug-susceptibility testing. Including use of the GeneXpert has the capacity to improve the diagnosis of TBM cases.

A1C Variability Predicts Incident Cardiovascular Events, Microalbuminuria, and Overt Diabetic Nephropathy in Patients With Type 1 Diabetes Johan Wadén 1 , 2 , Carol Forsblom 1 , 2 , Lena M. Thorn 1 , 2 , Daniel Gordin 1 , 2 , Markku Saraheimo 1 , 2 and Per-Henrik Groop 1 , 2 1 Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland; 2 Department of Medicine, Division of Nephrology, Helsinki University Central Hospital, Helsinki, Finland. Corresponding author: Per-Henrik Groop, per-henrik.groop{at}helsinki.fi . Abstract OBJECTIVE Recent data from the Diabetes Control and Complications Trial (DCCT) indicated that A1C variability is associated with the risk of diabetes microvascular complications. However, these results might have been influenced by the interventional study design. Therefore, we investigated the longitudinal associations between A1C variability and diabetes complications in patients with type 1 diabetes in the observational Finnish Diabetic Nephropathy (FinnDiane) Study. RESEARCH DESIGN AND METHODS A total of 2,107 patients in the FinnDiane Study had complete data on renal status and serial measurements of A1C from baseline to follow-up (median 5.7 years), and 1,845 patients had similar data on cardiovascular disease (CVD) events. Intrapersonal SD of serially measured A1C was considered a measure of variability. RESULTS During follow-up, 10.2% progressed to a higher albuminuria level or to end-stage renal disease, whereas 8.6% had a CVD event. The SD of serial A1C was 1.01 versus 0.75 ( P < 0.001) for renal status and 0.87 versus 0.79 ( P = 0.023) for CVD in progressors versus nonprogressors, respectively. In a Cox regression model, SD of serial A1C was independently associated with progression of renal disease (hazard ratio 1.92 [95% CI 1.49–2.47]) and of a CVD event (1.98 [1.39–2.82]) even when adjusting for mean A1C and traditional risk factors. Interestingly for CVD, mean serial A1C itself was not predictive even though SD of A1C was. CONCLUSIONS In patients with type 1 diabetes, A1C variability was not only predictive of incident microalbuminuria and progression of renal disease but also of incident CVD events. Footnotes The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Received May 8, 2009. Accepted July 14, 2009. © 2009 American Diabetes Association

Background: Commercially available testosterone immunoassays give divergent results, especially at the low concentrations seen in women. We compared immunoassays and a nonimmunochemical method that could quantify low testosterone concentrations. Methods: We measured serum testosterone in 50 men, 55 women, and 11 children with use of eight nonisotopic immunoassays, two isotopic immunoassays, and isotope-dilution gas chromatography–mass spectrometry (ID/GC-MS). Results: Compared with ID/GC-MS, 7 of the 10 immunoassays tested overestimated testosterone concentrations in samples from women; mean immunoassay results were 46% above those obtained by ID/GC-MS. The immunoassays underestimated testosterone concentrations in samples from men, giving mean results 12% below those obtained by ID/GC-MS. In women, at concentrations of 0.6–7.2 nmol/L, 3 of the 10 immunoassays gave positive mean differences >2.0 nmol/L (range, −0.7 to 3.3 nmol/L) compared with ID/GC-MS; in men at concentrations of 8.2–58 nmol/L, 3 of the 10 immunoassays tested gave mean differences >4.0 nmol/L (range, −4.8 to 2.6 nmol/L). Conclusion: None of the immunoassays tested was sufficiently reliable for the investigation of sera from children and women, in whom very low (0.17 nmol/L) and low (<1.7 nmol/L) testosterone concentrations are expected.

To the Editor: Within a 3-week period, two women, 46 and 48 years of age, presented with peripheral neuropathy and associated pancytopenia with macrocytic anemia. Clinical suspicion for pernicious anemia was high, but vitamin B 12 levels were 1644 pg per milliliter (1228 pmol per liter) and 1321 pg per milliliter (975 pmol per liter), respectively (reference range, 246 to 1320 pg per milliliter [181 to 974 pmol per liter]). On subsequent bone-marrow evaluation, specimens from both patients showed profound megaloblastic features. Additional findings on laboratory tests included elevated levels of homocysteine and methylmalonic acid combined with detection of intrinsic . . .