Evaluation of the hypochromic erythrocyte and reticulocyte hemoglobin content provided by the Sysmex XE-5000 analyzer in diagnosis of iron deficiency erythropoiesis.

BACKGROUND: Iron deficiency represents the most frequent cause of anemia. To diagnose iron deficiency some biochemical tests such as serum ferritin and the transferring saturation percent (TSAT%) are usually used. Recently, some hematological parameters such as mean reticulocyte hemoglobin content (CHr or Ret-He) and percentage of hypochromic RBCs (Hypo% or %Hypo-He) were proposed as alternative to biochemical tests. In this study, the analytic performance and the diagnostic efficiency of these two parameters provided by Sysmex XE5000 analyzer on iron deficiency patients with or without anemia (IDA and ID, respectively) were evaluated. METHODS: One hundred and sixty-four healthy adults, 58 with IDA, 21 with iron depleted stores (ID), 23 with ß-thalassemia trait, and 24 with non iron deficiency anemia were selected. The gold standard used to define iron deficiency was the coexistence of serum ferritin below 15 µg/L (12 in women) and TSAT <16%. RESULTS: For %Hypo-He, the best cut-off value for both IDA and ID is 0.9% while for Ret-He is 30.6 pg. For both parameters the performance was better to diagnose IDA (AUC, 0.96 and 0.98) than ID (AUC, 0.93 and 0.95). The Ret-He behavior was always slightly better than that of %Hypo-He. CONCLUSIONS: The use of these two parameters is useful to detect iron deficiency conditions if the hemoglobin synthesis has already been compromised.

Diagnosis of iron deficiency in patients undergoing hemodialysis.

To diagnose iron deficiency in patients undergoing hemodialysis, the percentage of hypochromic RBCs (with cellular hemoglobin concentration <280 g/L [HYPO%]) and mean reticulocyte hemoglobin content (CHret) provided by the Siemens ADVIA 120 and 2120 analyzers (Siemens Diagnostic Solutions, Tarrytown, NY) were proposed as alternatives to biochemical tests. Sysmex, with its XE-5000 analyzer (Sysmex, Kobe, Japan), also proposed the percentage of erythrocytes with cellular hemoglobin content lower than 17 pg (%Hypo-He) and equivalent of the mean reticulocyte hemoglobin content (Ret-He) with similar clinical applications. Our aim was to verify the clinical usefulness of the biochemical and cellular parameters as predictors of iron deficiency in patients undergoing long-term hemodialysis. We studied 69 patients undergoing hemodialysis 3 times weekly. The baseline values of serum ferritin and percentage of transferrin saturation were poor predictors of iron responsiveness. Better ability was demonstrated by reticulocyte indices (area under the curve [AUC], 0.74 for CHret and 0.72 for Ret-He; best cutoff values, 31.2 and 30.6 pg, respectively) and erythrocyte parameters (AUC, 0.72 for HYPO% and 0.68 for %Hypo-He; best cutoff values, 5.8 and 2.7, respectively). The newly proposed Ret-He and %Hypo-He can provide clinicians with information equivalent to CHret and HYPO%.

Precision performance at low levels and 99th percentile concentration of the Access AccuTnl assay on two different platforms.

BACKGROUND: Cardiac troponins currently represent the preferred biomarkers for the detection of myocardial necrosis. The objective of the present study was to compare the performance of the Access AccuTnl assay (Beckman Coulter) measured on two different platforms, the UniCel Dxl 800 and the Access 2 (Beckman Coulter). In particular, the serum cardiac troponin I (cTnl) concentration corresponding to 10% coefficient of variation (CV), the cTnl assay minimum detectable concentration (MDC), and the serum cTnl 99th percentile in healthy subjects were calculated. METHODS: The Access AccuTnl is a paramagnetic particle chemiluminescent immunoassay. Imprecision profiles were determined according to the Clinical and Laboratory Standards Institute EP5-A protocol using serum pools. The MDC was calculated as mean +3 SD of 20 determinations of the zero calibrator during one run. The 99th percentile was determined analyzing serum samples from 679 healthy blood donors (523 males, 156 females; 18-71 years old). RESULTS: cTnl concentrations are given in microg/L. 10% CV values (95% confidence interval, CI) were 0.0577 (0.0467-0.0750) (UniCel Dxl 800) and 0.0486 (0.0255-0.0596) (Access 2). MDC values were 0.011 (UniCel Dxl 800) and 0.012 (Access 2). The 99th percentile (95% CI) value was 0.0340 (0.0298-0.0410). CONCLUSIONS: Our data confirm the reliability of the evaluated cTnl assay and demonstrate the comparability of the cTnl values between the platforms studied.

Analytical and clinical performance of a fully automated cardiac multi-markers strategy based on protein biochip microarray technology.

OBJECTIVES: The analytical and clinical performance of the Evidence Cardiac Panel were evaluated. DESIGN AND METHODS: The Evidence Cardiac Panel, an automated protein biochip microarray system, allows the simultaneous determination of creatine kinase MB (CK-MB), myoglobin (MYO), glycogen phosphorylase BB (GPBB), heart-type fatty acid-binding protein (H-FABP), carbonic anhydrase III (CA III), cardiac troponin I (cTnI). Precision: 3 levels of quality control (QC) and 2 in house pools (P) were assayed. Method comparison: MYO and cTnI concentrations measured on Evidence (E) and on Dimension RxL (D) analyzers were compared. Clinical study: 132 non-consecutive patients admitted to the Emergency Department for chest pain were enrolled. RESULTS AND CONCLUSIONS: The between-day imprecision was CK-MB=6.80-10.08%; MYO=5.36-16.50%; GPBB=6.51-12.12%; H-FABP=6.26-12.63%; CA III=6.98-13.61%; cTnI=6.02-9.80%. Method comparison: E-MYO vs. D-MYO, Bias=-29.22, 95% CI from -40.25 to -18.18; E-cTnI vs. D-cTnI, Bias=-2.75, 95% CI from -4.04 to -1.46. In patients studied (at discharge: AMI, acute myocardial infarction n=42; non-AMI, n=90) H-FABP showed the highest accuracy (ROC analysis, AUC=0.92) and "cTnI+H-FABP" the greatest diagnostic efficacy (89.4%) in AMI diagnosis.

New biochemical markers: from bench to bedside.

BACKGROUND: Evaluation of patients presenting to hospital with chest pain or other signs or symptoms suggesting acute coronary syndrome (ACS) is problematic, time-consuming and sometimes expensive, even if new biochemical markers, such as troponins, have improved the ability to detect cardiac injury. However, patients with normal troponin values are not necessarily risk-free for major cardiac events. METHODS: Recent investigations indicate that the overall patient risk may be assessed earlier than before, thanks to new knowledge acquired concerning the pathobiology of atherosclerosis and molecular events involved in the progression of disease, thus allowing the development of new biochemical markers. Some selected markers are released during the different phases of development of cardiovascular disease and may be useful for the diagnosis of patients with cardiovascular disease. In particular, the identification of emerging markers that provide relevant information on the inflammatory process, and the development of biomarkers whose circulating concentrations suggest the status of plaque instability and rupture, seems to be of particular value in prognosis and risk stratification. The overall expectations for a cardiovascular biochemical marker are not only its biological plausibility but also the availability at a reasonable cost of rapid, high quality assays, and their correct interpretation by clinicians using optimal cut-offs. CONCLUSION: The crossing from bench to bedside for each new marker discovered, must be associated with concurrent advances in the characterization of analytical features and the development of routine assay, in the assessment of analytical performance and in interpretative reporting of test results as well as in the training of physicians to use the array of biomarkers available appropriately and to interpret them correctly. This approach calls for the coordinated support of clinicians, technology experts, statisticians and the industry so that new biochemical developments can be of optimal value.

Analytical and clinical evaluation of a new heart-type fatty acid-binding protein automated assay.

BACKGROUND: The accurate and rapid recognition of myocardial injury in patients presenting in the emergency department (ED) with chest pain continues to be a clinical challenge. Heart-type fatty acid-binding protein (H-FABP) appears to be one of the best candidates among the new early cardiac markers studied. METHODS: We evaluated the analytical characteristics of a new quantitative and fully automated H-FABP assay (Randox Laboratories Ltd., Crumlin, UK) and compared its clinical performance with respect to the myoglobin (Myo) assay (Dade Behring, Milan, Italy). A precision study was carried out by testing three levels of quality control (QC) material and two in-house pool (P) samples. To test the accuracy of H-FABP determinations in plasma (lithium-heparin) samples, H-FABP concentrations measured in a set of matched sera and plasma samples were compared. A total of 77 non-consecutive patients (51 males and 26 females; 62+/-16 years) who presented to the ED with chest pain suggesting myocardial ischemia were enrolled. The patients were classified into two groups (acute myocardial infarction, n=22; non-acute myocardial infarction, n=55) on the basis of the discharge diagnosis. RESULTS: The between-day imprecision for three levels of control material and serum pool samples was 6.26%-8.04% (range 2.32-44.03 microg/L) and 9.03%-12.63% (range 11.85-65.13 microg/L), respectively. In the serum vs. plasma study, bias was +0.178 (95% CI -0.033 to +0.389). The best cut-off and the associated diagnostic efficacy were 95 microg/L and 89.47% for Myo and 5.09 microg/L and 98.70% for H-FABP, respectively. CONCLUSIONS: H-FABP determination in patients with ischemic symptoms may be a more reliable early indication of cardiac damage than myoglobin.