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PubMed1994

Lyme disease: laboratory diagnosis and serologic testing.

Although identified less than 20 years ago, Lyme disease has proved to be the most common tick-borne disease in the United States: some 10,000 cases were reported in 1992. In some cases the disease may be transitory and of little consequence but in others it may become chronic and severely disabling. Accurate diagnosis is, therefore, of great importance but, as this article shows, laboratory testing techniques still need improvement.

Antibodies, Bacterial↗
PubMed1986

Laboratory diagnosis of cocaine: intoxication and withdrawal.

The clinical diagnosis of cocaine abuse is more difficult than previously recognized. The laboratory can play an important role in helping identify cocaine abusers and also in monitoring the progress of their recovery. An overview of the role of the laboratory is presented with the goal of optimizing the clinician's ability to apply available technology in an efficient manner. Various chromatographic and competitive binding techniques for the detection of cocaine and its metabolites in biological fluids are discussed and limits of each technique is identified. The cases of false negative and false positive results are explored and an approach to maximize benefits and economics of testing is described.

Arousal↗
PubMed2000

Polymerase chain reaction for the laboratory diagnosis of aseptic meningitis and encephalitis.

A protocol for testing cerebrospinal fluid specimens using a range of PCR assays for the diagnosis of central nervous system infection was developed and used to test prospectively 383 specimens. PCR assays were used for the detection of adenovirus, Borrelia burgdorferi, enteroviruses, Epstein Barr virus, cytomegalovirus, herpes simplex virus, human herpes virus type 6, JC virus, Leptospira interrogans, Listeria monocytogenes, lymphocytic choriomeningitis virus, measles virus, mumps virus, Mycobacterium sp. , Mycoplasma pneumoniae, Toxoplasma gondii and varicella zoster virus. Of the 383 specimens tested in this study, 46 (12.0%) were found to be positive. The microorganisms detected were CMV, enterovirus, Epstein Barr virus, herpes simplex virus, human herpes virus type 6, JC virus, L. monocytogenes, Mycobacterium genus, Toxoplasma gondii and varicella zoster virus. The introduction of the PCR protocol described has improved the diagnosis of a range of central nervous system infections in our laboratory. We believe however that further evaluation of these assays in immunocompromised patients is necessary to better determine the predictive value of positive PCR results in these patient groups.

Adolescent↗
PubMed1988

Computer assisted laboratory diagnosis: a ten-year experience.

An automated procedure to help general practitioners in clinical diagnosis and decision making is presented. The computer-based program is conceived to process results from laboratory tests performed on outpatients, providing general practitioners with possible causes of abnormal results. When only one or two abnormal tests are observed, a series of suggestions pertinent to each abnormality is printed. When there are more abnormal test results, the program performs a more complex procedure ending with the output of some diagnostic hypotheses. Messages are also printed to focus the physician's attention to particular aspects of patient pathology that were sometimes missed or disregarded and to suggest new investigations the laboratory can perform to improve diagnostic efficiency. Moreover some advice is supplied to allow a better evaluation of particular risk conditions, as those associated with the development of coronary heart disease. The program has been recently extended with the calculation of intraindividual reference intervals. The system described has been working since 1976 and appears particularly useful when the general practitioner is faced with a number of pathological results of difficult interpretation.

Adolescent↗
PubMed1991

Laboratory diagnosis of malaria.

Diagnostic procedures for the detection of malaria differ considerably depending on the aims of evaluation. The current requirements of any laboratory procedure for general application to the detection and diagnosis of malaria include: sensitivity, specificity, simplicity in application, unambiguous interpretation, and rapid turn-around time. Presently the differential stained thick and thin blood smear, examined under the microscope, remains the most reliable and definitive test for diagnosis of malaria.

Animals↗
PubMed2005

External quality assessment and the laboratory diagnosis of thrombophilia.

External quality assessment is a tool to compare the result of a particular laboratory test in relation to those of other laboratories as well as to assess the performance of a laboratory test over a prolonged period of time. We evaluated the relationship between the between-laboratory variation and the sample category (normal, borderline, and abnormal) for antithrombin, protein C, protein S, and the activated protein C resistance test. Only for antithrombin and protein S was a significant relationship (0.004 < p < 0.012) observed. The effect of the between-laboratory variation of the different sample categories on the clinical interpretation was investigated. With the exception of free protein S antigen, all variables showed a significant relationship (0.004 < p < 0.045) between the sample category and the percentage of misclassification. Because in clinical practice a stable test performance over a prolonged period of time is important, we evaluated the quality of test performance using the long-term analytical coefficient of variation (LCVa). A wide range in the LCVa was observed for antithrombin, protein C, and protein S. Less than half of the participants could fulfill the quality specification for diagnostic testing (LCVa < or = 0.58 x total biological variation). This study shows that a more stable performance of laboratory tests involved in the screening of thrombophilia over a prolonged period of time is necessary.

Antithrombins↗
PubMed2004

Laboratory diagnosis of legionnaires' disease due to Legionella pneumophila serogroup 1: comparison of phenotypic and genotypic methods.

Laboratory results of 67 cases of legionnaires' disease caused by Legionella pneumophila serogroup (Sg) 1 spanning a 6-year period were analysed by both phenotypic and genotypic methods. The methods compared were urinary antigen enzyme immunoassay (EIA), an immunofluorescent antibody (IFA) test, direct fluorescent antibody (DFA), culture and a 5S rRNA PCR with Southern blotting confirmation. Urine was available in 53 cases, of which 35 (66%) were positive, with an antigen peak observed at 5-10 days after onset of disease symptoms. The IFA test was positive in 62 (92.5%) cases, with 56 (90.3%) cases producing a greater than fourfold rise in titre and 6 (9.7%) giving presumptive high titres of > or =1:128. There were two antibody peaks, one at 10-15 days and another at >25 days after onset. In 23 cases where samples were available, DFA and culture were respectively positive in 5 (22%) and 10 (48%) cases. There was a peak in culture-positives 5-10 days after onset of disease. A Legionella-specific 5S rRNA PCR on patient serum was positive in 54 (80.5%) cases, with a peak in PCR positivity at 6-10 days after disease onset. In 22 of the 67 cases, the full panel of diagnostic methods was available for comparison. The relative sensitivity and specificity of the urinary antigen EIA and the serum PCR was 100%. The IFA gave relative sensitivity and specificity values of 93.8 and 95%. DFA and culture, although 100% specific, produced only low sensitivities, of 19 and 42.8%, respectively. This study has shown that urinary antigen and serum PCR are valuable tests in the acute phase of disease, with excellent sensitivity and specificity values. At present, the Legionella species causing infection requires to be verified by IFA serology and/or culture, but this could become unnecessary as new antigen and L. pneumophila Sg 1-specific PCR tests become available.

Adult↗
PubMed1990

[Quality assurance in clinical laboratory diagnosis].

Both the internal and the external quality controls are necessary to achieve reliable and comparable laboratory tests. The internal quality control includes preanalytical, analytical and postanalytical checking of factors to eliminate all interferences of laboratory tests. The use of reliable methods which result in a good accuracy and precision, however, can provide results which are not comparable to the results of other laboratories. The role of the external quality control is to check differences between the laboratories and to make the results as comparable as possible. The accuracy and precision of Hungarian laboratories improved during the past decade which can be attributed to the better technical conditions, on the one hand, and to the regular internal and external quality control, on the other hand. An increasing number of the small laboratories, mostly in the service of general practitioners, are unable to perform the same quality of laboratory tests as that of the central laboratories, since their technical conditions are old-fashioned and inadequate to use up-to-date methods. The urgency of improvement in technical condition of small laboratories is obvious from both professional and economical reasons.

Clinical Laboratory Techniques↗
PubMed2004

Laboratory diagnosis of von Willebrand's disorder: quality and diagnostic improvements driven by peer review in a multilaboratory test process.

Regular multilaboratory surveys of laboratories derived primarily from Australia, New Zealand and Southeast Asia have been conducted over the past 7 years to evaluate testing proficiency in the diagnosis of von Willebrand's disorder (VWD) and to assess changes to test practice. Participating laboratories (currently 45) are asked to perform their usual panel of tests for VWD, and then to self-interpret test results as to the likelihood (or not) of VWD, as well as to the potential subtype identified. Samples provided in the past two survey distributions (both conducted in 2003) were as follows. Survey part A/distribution 1: Normal donor plasma, plasma with borderline normal/reduced levels of VWF (x2) and plasma from an individual with type 2 A VWD. Survey part B/distribution 2 (family VWD study): Plasma from a father, mother and son with borderline normal/reduced von Willebrand factor (VWF), and a daughter with type 3 VWD. In line with previously published survey results, the interassay and within method coefficients of variation (CV) were similar for all assays (around 15-25%), although tending to be slightly higher for VWF:RCo and VWF:CB than VWF:Ag and FVIII:C. Most laboratories reported test values consistent with expected findings, and made correct interpretations or predictions regarding the nature of the samples, although discrepant assay results or interpretations are still seen in approximately 5-10% of responses (typically from laboratories using a more limited test panel or not performing the VWF:CB). Overall, problems with the non-identification of functional VWF discordance in type 2 VWD, the misidentification of functional VWF discordance in type 1 VWD, and difficulties in discriminating types 1 and 3 VWD appear to predominate. In comparison with previous surveys, performance of electro-immuno diffusion (EID) (or Laurel gel) procedures has now ceased, and a reduction in VWF:RCo and VWF:Multimer testing and an increase in latex immunoassay (LIA) testing is sustained. We conclude that laboratories are generally proficient in tests for VWD, and that diagnostic error rates are reduced when test panels are more comprehensive and include the VWF:CB.

Clinical Laboratory Techniques↗
PubMed1999

Standardization on laboratory diagnosis of thalassemia and abnormal hemoglobin.

Thalassemia is one of the most common single gene disorders. The geographic distribution of thalassemia and abnormal hemoglobin has been known for many years. A worldwide significant spread of these abnormal genes, especially from Southeast Asia, occurred in the last two decades. This has resulted in a dramatic increase of Hb E disorders and various Southeast Asian thalassemia genotypes, which means that requests for hemoglobinopathy investigations are likely to increase in many laboratories worldwide. Hemoglobinopathy screening and diagnosis may need to be undertaken antenatally, neonatally and in certain hematological situations. The introduction of automation for hemoglobinopathy screening, including the automated cell counting and HPLC system, is an important advance in technology for hematology laboratories. The instruments need to be calibrated and standardized to get an accurate data for interpretation. Internal and external control samples are also needed. Combination of test results is usually required to achieve a proper diagnosis, which in turn, provide a self-check for each laboratory test.

Adult↗
PubMedDate not supplied

Strategies for the laboratory diagnosis of some common causes of anaemia in elderly patients.

Anaemia is a common medical problem in elderly patients and is associated with an increased mortality and morbidity risk and a reduced quality of life. It is not known at which exact haemoglobin level investigations should be initiated in order to optimize the diagnostic efficacy. Serum ferritin determination remains the most accurate laboratory test for the diagnosis of iron deficiency anaemia and its differential diagnosis with the anaemia of chronic disease. The introduction of the metabolites methylmalonic acid and homocysteine has made it possible to diagnose vitamin B(12) and folate deficiencies at an early subclinical stage, even without neurological and haematological symptoms, but the clinical importance of this 'biochemical' diagnosis is unclear. Other causes of anaemia, such as myelodysplastic syndromes and chronic renal insufficiency, will become more and more common in the elderly because of the ageing of the population. Although erythropoietin analysis has no clear diagnostic value at the moment, it has become more and more obvious that its therapeutic importance in elderly patients with chronic anaemia is increasing. A substantial number of patients have an unexplained anaemia. Whether this is disease related, or may be attributed to an age-related anaemia, is still a matter of debate, but it is advisable to perform an extensive laboratory, cytogenetic, and morphological investigation before one should assess the anaemia as unexplained.

Aged↗
PubMedDate not supplied

Laboratory diagnosis of foodborne diseases.

Many bacterial species are responsible for sporadic cases and outbreaks of foodborne intoxication and infection. The foodborne diseases are classified on the basis of the pathogenetic mechanisms involved into four categories: performed toxin, enterotoxin formed in the colonized small intestine, mucosal invasion (enterocolitis) and mucosal invasion with bacteremia. Invasive and toxigenic strains of enteropathogenic Escherichia coli are discussed. In vivo test systems for the identification of enterotoxigenic organisms and tissue culture assays for the heat-labile enterotoxin of E. coli are described. Current laboratory methods for the diagnosis of foodborne diseases of major public health interest are reviewed - botulism, staphylococcal intoxication, Clostridium perfringens enteritis, salmonellosis, enteropathogenic E. coli infection, Vibrio parahaemolyticus infection and Bacillus cereus enteritis. The role of the laboratory in the epidemiologic surveillance and investigation of foodborne diseases is emphasized.

Animals↗
PubMed2000

Laboratory diagnosis of patients with acute chest pain.

The enzyme activities of creatine kinase (CK), its isoenzyme MB (CK-MB) and of lactate dehydrogenase isoenzyme 1 (LD-1) have been used for years in diagnosing patients with chest pain in order to differentiate patients with acute myocardial infarction (AMI) from non-AMI patients. These methods are easy to perform as automated analyses, but they are not specific for cardiac muscle damage. During the early 90's the situation changed. First creatine kinase MB mass (CK-MB mass) replaced the measurement of CK-MB activity. Subsequently cardiac-specific proteins troponin T (cTnT) and troponin I (cTnI) appeared on the scene, displacing LD-1 analysis. However, troponin concentrations in blood increase only from four to six hours after onset of chest pain. Therefore a rapid marker such as myoglobin, fatty acid binding protein or glycogen phosphorylase BB could be used in early diagnosis of AMI. On the other hand, CK-MB isoforms alone may also be useful in rapid diagnosis of cardiac muscle damage. Myoglobin, CK-MB mass, cTnT and cTnI are nowadays widely used in diagnosing patients with acute chest pain. Myoglobin is not cardiac-specific and therefore requires supplementation with some other analyses such as troponins to support the myoglobin value. Troponins are very highly cardiac-specific. Only the sera of some patients with severe renal failure, which requires hemodialysis, have elevated cTnT and/or cTnI without there being any evidence of cardiac damage. On the other hand, the latest studies have shown that elevated troponin levels in sera of hemodialysis patients point to an increased risk of future cardiac events in a similar manner to the elevated troponin values in sera of patients with unstable angina pectoris. In addition, the bedside tests for cTnT and cTnI alone or together with myoglobin and CK-MB mass can be used instead of quantitative analyses in the diagnosis of patients with chest pain. These rapid tests are easy to perform and they do not require expensive instrumentation. For routine clinical laboratory practice we suggest that in diagnosis of patients with chest pain, myoglobin and CK-MB mass measurements should be performed whenever they are requested (24 h/day) and cTnT or cTnI on admission to the hospital and then 4-6 and 12 hours later.

Creatine Kinase↗