Prekallikrein deficiency in a 15-year-old boy with Ménière's disease: a case report.

Congenital prekallikrein deficiency is a rare disorder in which there is an in vitro clotting defect despite absence of bleeding or thrombotic tendency. In this report, a 15-year-old boy with an unexpected markedly prolonged activated partial thrombin time, a normal prothrombin time, and without personal nor familial history of bleeding or thrombosis is presented. Laboratory investigation revealed a severe prekallikrein deficiency. This case highlights the importance of following a diagnostic algorithm to establish the correct diagnosis. Moreover, by selecting appropriate laboratory tests, unnecessary and repeatedly testing can be avoided.

A novel approach for BCR-ABL1 standardization to improve International Scale estimation.

INTRODUCTION: Standardization of BCR-ABL1 messenger RNA quantification by real-time PCR on the International Scale (IS) is critical for monitoring therapy response in chronic myelogenous leukaemia. Since 2006, BCR-ABL1 IS standardization is propagated along reference laboratories by calculating a laboratory-specific conversion factor (CF), co-ordinated in Europe through the European Treatment and Outcome Study project. Although this process has proven successful to some extent, it has not been achievable for all laboratories due to the complexity of the process and the stringent requirements in terms of numbers of samples to be exchanged. In addition, several BCR-ABL1 IS quantification methods and secondary reference materials became commercially available. However, it was observed that different IS methods generate consistently different results. METHODS: To overcome these difficulties, we have developed an alternative and simple approach of CF calculation, based on the retrospective analysis of existing external quality assessment (EQA) data. Our approach does not depend on the exchange of samples and is solely based on the mathematical CF calculation using EQA results. RESULTS AND CONCLUSION: We have demonstrated by thorough statistical validation that this approach performs well in converting BCR-ABL1 measurements to improve IS estimation. In expectation of a true golden standard method for BCR-ABL1 IS quantification, the proposed method is a valuable alternative.

Detection of Giardia lamblia, Cryptosporidium spp. and Entamoeba histolytica in clinical stool samples by using multiplex real-time PCR after automated DNA isolation.

Diagnosis of intestinal parasites in stool samples is generally still carried out by microscopy; however, this technique is known to suffer from a low sensitivity and is unable to discriminate between certain protozoa. In order to overcome these limitations, a real-time multiplex PCR was evaluated as an alternative approach for diagnosing Giardia lamblia, Cryptosporidium spp. and Entamoeba histolytica in stool samples.Therefore, a total of 631 faecal samples were analysed both by microscopy as well as by real-time PCR following automated DNA extraction. Results showed that real-time PCR exhibited sensitivity and specificity of both 100%, whereas traditional microscopy exhibited sensitivity and specificity of 37.5% and 99.8% respectively. As real-time PCR provides simple, sensitive and specific detection of these three important pathogenic protozoan parasites, this technique, rather than microscopy, has become our diagnostic method of choice for the detection of enteric protozoan parasites for the majority of patients.

Validation of the minimal citrate tube fill volume for routine coagulation tests on ACL TOP 500 CTS®.

INTRODUCTION: CLSI recommends a minimal citrate tube fill volume of 90%. A validation protocol with clinical and analytical components was set up to determine the tube fill threshold for international normalized ratio of prothrombin time (PT-INR), activated partial thromboplastin time (aPTT) and fibrinogen. METHODS: Citrated coagulation samples from 16 healthy donors and eight patients receiving vitamin K antagonists (VKA) were evaluated. Eighty-nine tubes were filled to varying volumes of >50%. Coagulation tests were performed on ACL TOP 500 CTS(®) . Receiver Operating Characteristic (ROC) plot, with Total error (TE) and critical difference (CD) as possible acceptance criteria, was used to determine the fill threshold. RESULTS: Receiving Operating Characteristic was the most accurate with CD for PT-INR and TE for aPTT resulting in thresholds of 63% for PT and 80% for aPTT. By adapted ROC, based on threshold setting at a point of 100% sensitivity at a maximum specificity, CD was best for PT and TE for aPTT resulting in thresholds of 73% for PT and 90% for aPTT. For fibrinogen, the method was only valid with the TE criterion at a 63% fill volume. CONCLUSION: In our study, we validated the minimal citrate tube fill volumes of 73%, 90% and 63% for PT-INR, aPTT and fibrinogen, respectively.

Plasma D-dimer concentrations in different clinical conditions.

D-dimers (DD), specific degradation products of crosslinked fibrin, are markers for activation of plasma coagulation and/or fibrinolysis. DD results below the cut-off level are proven to be useful to rule out the probable diagnosis of deep venous thrombosis (DVT) and/or pulmonary embolism (PE). Our objective was to demonstrate that positive DD occur in many diseases and certain physiological conditions as high age and pregnancy and to look for gradations in positivity between different pathological conditions. We wanted to investigate the request attitude of our clinicians concerning DD. Positive DD results still confuse some physicians. Retrospectively, we examined medical records of 574 consecutive patients, in whom plasma DD were measured in daily routine. Both outpatients (n = 423) and inpatients (n = 151) were included. We noted their clinically predominant disease. Measurement of DD concentration is too often requested by clinicians, in any medical condition, and is not always clinically relevant. The relation of a positive result and the clinical problem is sometimes not understood. Overall, we found 64% DD positivity with a median concentration of 775 micrograms/L. We found elevated DD concentrations in various clinical conditions.

Use of an islet cell antibody assay to identify type 1 diabetic patients with rapid decrease in C-peptide levels after clinical onset. Belgian Diabetes Registry.

OBJECTIVE: To investigate whether the presence of antibody markers at diagnosis could help predict the rapid decrease in residual beta-cell function noted in some, but not all, patients with recent-onset type 1 diabetes. RESEARCH DESIGN AND METHODS: We measured random C-peptide levels (radioimmunoassay); islet cell cytoplasmic antibodies (ICA) (indirect immunofluorescence); and antibodies against IA-2 protein, 65-kDa glutamate decarboxylase, and insulin (liquid-phase radiobinding assays) in 172 patients <40 years of age with type 1 diabetes. The patients had been consecutively recruited at diagnosis by the Belgian Diabetes Registry and were followed for 2 years. RESULTS: Two years after diagnosis, random C-peptide levels had decreased significantly (P < 0.001) in ICA+ patients but not in ICA- patients. C-peptide values <50 pmol/ were noted in 88% of patients diagnosed before 7 years of age, in 45% of patients diagnosed between ages 7 and 15 years, and in 29% of patients diagnosed after 15 years of age (P < 0.001). In cases of clinical onset before age 15 years, a rapid decline in random C-peptide values was observed almost exclusively in patients with high-titer ICA (> or =50 Juvenile Diabetes Foundation [JDF] units) at diagnosis (69 vs. 17% in patients with lower ICA titers, P < 0.001). In patients diagnosed after 15 years of age, 36% of patients with ICA titers > or =12JDF units developed low C-peptide levels compared with 14% of patients with ICA titers < 12 JDF units (P < 0.03). Multivariate analysis confirmed that C-peptide levels after 2 years were inversely correlated with ICA levels (P < 0.001) and to a lesser degree positively correlated with age at diagnosis (P < 0.02), regardless of the levels or number of molecular autoantibodies. CONCLUSIONS: Young age at diagnosis and high-titer ICA identify a group of type 1 diabetic patients at high risk of rapidly losing residual beta-cell function. Using these selection criteria, it is possible to better target beta-cell-preserving interventions to patients with or without such rapid progression, depending on the nature of the tested substance. The ICA assay measures clinically relevant antibodies not detected in antibody assays that use recombinant human autoantigens for substrate.

Cardiac troponins I and T are biological markers of left ventricular dysfunction in septic shock.

BACKGROUND: Cardiac depression in severe sepsis and septic shock is characterized by left ventricular (LV) failure. To date, it is unclear whether clinically unrecognized myocardial cell injury accompanies, causes, or results from this decreased cardiac performance. We therefore studied the relationship between cardiac troponin I (cTnI) and T (cTnT) and LV dysfunction in early septic shock. METHODS: Forty-six patients were consecutively enrolled, fluid-resuscitated, and treated with catecholamines. Cardiac markers were measured at study entry and after 24 and 48 h. LV function was assessed by two-dimensional transesophageal echocardiography. RESULTS: Increased plasma concentrations of cTnI (>/=0.4 microgram/L) and cTnT (>/=0.1 microgram/L) were found in 50% and 36%, respectively, of the patients at one or more time points. cTnI and cTnT were significantly correlated (r = 0.847; P <0.0001). Compared with cTnI-negative patients, cTnI-positive subjects were older, presented higher Acute Physiology and Chronic Health Evaluation II scores at diagnosis, and tended to have a worse survival rate and a more frequent history of arterial hypertension or previous myocardial infarction. In contrast, the two groups did not differ in type of infection or pathogen, or in dose and type of catecholamine administered. Continuous electrocardiographic monitoring in all patients and autopsy in 12 nonsurvivors did not disclose the occurrence of acute ischemia during the first 48 h of observation. LV dysfunction was strongly associated with cTnI positivity (78% vs 9% in cTnI-negative patients; P <0.001). In multiple regression analysis, both cTnI and cTnT were exclusively associated with LV dysfunction (P <0.0001). CONCLUSIONS: These findings suggest that in septic shock, clinically unrecognized myocardial cell injury is a marker of LV dysfunction. The latter condition tends to occur more often in severely ill older patients with underlying cardiovascular disease. Further studies are needed to determine the extent to which myocardial damage is a cause or a consequence of LV dysfunction.

Analytic and clinical evaluation of the Abbott AxSYM cardiac troponin I assay.

We evaluated the AxSYM immunoassay for the quantification of cardiac troponin I (cTnI). Total assay imprecision, expressed as coefficient of variation, ranged between 5.6% and 8.3% for commercial control serum samples and between 4.2% and 13.9% for pooled patient samples. Linearity was verified up to 42 micrograms/L. Triglycerides (up to 1,000 mg/dL) did not interfere with the assay, but minor hemolysis and clinically relevant hyperbilirubinemia caused a negative bias. In 186 patient samples, AxSYM cTnI levels correlated significantly with data obtained with the Stratus II cTnI fluorometric enzyme immunoassay but were 3 to 4 times higher on AxSYM than on Stratus II. In 111 healthy blood donors, the reference range for cTnI levels on AxSYM was 0.0 to 0.4 microgram/L. After eccentric isokinetic exercise, healthy volunteers showed a rise in creatine kinase MB mass (AxSYM) but not in cTnI. On AxSYM and Stratus II, cTnI levels increased above the manufacturer's cutoff for acute myocardial infarction in all 17 patients followed up after onset of infarction-related chest pain but in only 1 of 91 control subjects. The AxSYM cTnI assay is a valid alternative for the detection of myocardial injury with diagnostic performance comparable to the established Stratus cTnI assay.