RESUMEN
As part of a symposium on laboratory medicine, a colloquium on point-of-care testing was held in June 1999 where four experts were invited to produce recommendations and opinions on the use of point-of-care testing under various clinical venues. Each commented on costs for providing POCT services. A total of eleven recommendations and four opinions were rendered and discussed in an open forum. While one expert concluded that some forms of POCT are less expensive than central laboratory testing if entire laboratory workstations are eliminated, another expert suggested that POCT offered little advantage if rapid transport systems are available. A recommendation was made that POCT be considered for analytes that have a required reporting turnaround time of <30 min, and that the goals for precision and accuracy should be dictated by the clinical need and not by analytical limitations. Recommendations for POCT in specific clinical situations include use of glycated hemoglobin and urine albumin testing with personal glucose monitoring at the time of consultation, use of glycated albumin for gestational diabetes, leukocyte esterase and nitrite testing in urine to screen for urinary tract infections, coagulation tests for monitoring patients on oral anticoagulant therapy and in the operating room, testing for H. pylori for patients with dyspepsia, and cardiac markers and urine drugs-of-abuse testing in the emergency department.
Asunto(s)
Laboratorios de Hospital/organización & administración , Sistemas de Atención de Punto , Atención Primaria de Salud/organización & administración , Sistemas de Atención de Punto/economía , Sistemas de Atención de Punto/normas , Sensibilidad y EspecificidadRESUMEN
A network of national and international guidelines and directives developed in the last few decades by various bodies will lead to a new concept of total quality for medical laboratory services comprising legislative regulations on national and international levels, standardizations backed up by legislation and recommendations of professional societies. One example is the IVD Directive of the European Community. It will not only stimulate accreditation in the field of laboratory medicine, but also necessitate numerous standardization activities which are presently co-ordinated by the European Committee for Standardization (CEN). Another standardization example is the development of quality management systems, mainly by ISO. The ISO 9000 series has become the most successful family of standards world-wide. Meanwhile, specific standards for the needs of laboratories (ISO 17025), and in particular of medical laboratories (ISO 15189), are being worked out. A new trend to develop quality management systems towards total quality management systems can be observed including additional aspects such as economic and quality interests of society, customers and owners of laboratories. The goal of all activities is to create a network of confidence which provides some guarantee to the clients, i.e. the physicians and their patients, that they will receive a high-quality medical laboratory service.
Asunto(s)
Técnicas de Laboratorio Clínico/normas , Laboratorios/legislación & jurisprudencia , Laboratorios/normas , Europa (Continente) , Humanos , Control de CalidadRESUMEN
Several international standards and corresponding interpretation documents for quality management systems have been published. Although these standards are found useful to some extent, they are considered to be insufficient in several areas important for medical laboratories particularly in the pre- and post-examinational phases. The normative document for accreditation of laboratories (ISO/IEC Guide 25) is presently being revised and a document for medical laboratories (ISO/TC 212, CD 15189) is at draft stage. Both aim to include aspects of total quality management. The concept of total quality management is rather vague. Generally, its goal has been defined as "business excellence". This term, however, needs some explanation if applied to medical laboratories. Therefore, a project group of the European Confederation of Laboratory Medicine (ECLM) has developed a model for total quality management, which is based on a comprehensive management concept issued by the European Foundation for Quality Management. In the case of a medical laboratory, the term "business excellence" should be replaced by "good medical laboratory services". The proposed model could serve as a basis for future developments of total quality management standards in laboratory medicine. The goal of the "journey" should be clarified before it starts. To the best of our knowledge, this is the first attempt to develop a model of a good medical laboratory.
Asunto(s)
Laboratorios/normas , Modelos Organizacionales , Acreditación , Laboratorios/organización & administración , Objetivos Organizacionales , Gestión de la Calidad TotalRESUMEN
The analytical performance of the tumour markers CA 15-3 assay, CA 19-9 assay and Ca 125 II assay on the Bayer Immuno I System was studied according to a revised version of the ECCLS guidelines (Haeckel R. In: Evaluation methods in laboratory medicine, Weinheim, VCH Verlag 1993:47-69) in a multicentre evaluation involving five laboratories. Determination of the 3 analytes generated more than 6000 data. On the Bayer Immuno I System, the imprecisions of the CA 15-3 assay, CA 19-9 assay and CA 125 II assay were better than those found for comparison methods. The median recovery over all five laboratories of system assigned values in control sera was within the 1-s range for the three tumour marker assays. No deviation of linearity could be detected experimentally for all assays. Results for patients' samples showed acceptable agreement between the Bayer Immuno 1 system and several different comparison methods in most cases. One exception was the CA 15-3 assay in comparison with the MCA assay from Roche Diagnostic Systems, where the large difference in values is due to the use of different antibodies and calibrators in the two assays. No carry-over effects could be detected. The selective Bayer Immuno 1 system is fully automated; its practicability was rated as high.
Asunto(s)
Antígenos de Carbohidratos Asociados a Tumores/sangre , Biomarcadores de Tumor/sangre , Inmunoensayo/métodos , Antígenos de Carbohidratos Asociados a Tumores/inmunología , Biomarcadores de Tumor/inmunología , Biomarcadores de Tumor/normas , Antígeno Ca-125/sangre , Antígeno Ca-125/inmunología , Antígeno CA-19-9/sangre , Antígeno CA-19-9/inmunología , Humanos , Inmunoensayo/normas , Modelos Lineales , Mucina-1/sangre , Mucina-1/inmunología , Control de Calidad , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Factores de TiempoRESUMEN
UNLABELLED: This study investigates the application of PET with specific substrates for the assessment of enzyme activity after transfer of the herpes simplex virus thymidine kinase (HSV-tk) gene. METHODS: After transfection of a rat hepatoma cell line with a retroviral vector containing the HSV-tk gene, different clones were established by G418 selection. Uptake measurements were performed up to 48 hr in a TK-expressing cell line and in a control cell line using thymidine (TdR; measured under therapy conditions), fluorodeoxycytidine (FdCyt) and ganciclovir (GCV). Additionally, bystander experiments and inhibition/competition studies were done. RESULTS: In TK-expressing cells GCV treatment caused an increased (up to 250%) TdR uptake in the acid-soluble fraction and a decrease to 5.5% in the acid-insoluble fraction. The FdCyt uptake was higher in the TK-expressing cells than in controls with a maximum after 4 hr (12-fold and 3-fold higher in the acid-insoluble and acid-soluble fraction). GCV accumulated up to 180-fold more in the acid-insoluble and 26-fold more in the acid-soluble fraction. GCV uptake occurred mainly by the nucleoside transport systems. Bystander experiments revealed a relation between growth inhibition or GCV uptake and the amount of TK-expressing cells. GCV uptake and growth inhibition were correlated with r = 0.96. CONCLUSION: Assessment of GCV accumulation may serve as an indicator of the enzyme activity and of therapy outcome. TdR may be useful to measure therapy effects on DNA synthesis, whereas the potential of FdCyt has to be investigated in further studies.
Asunto(s)
Genes Virales , Terapia Genética , Neoplasias Hepáticas Experimentales/diagnóstico por imagen , Neoplasias Hepáticas Experimentales/terapia , Simplexvirus/genética , Timidina Quinasa/genética , Tomografía Computarizada de Emisión , Animales , Antivirales/farmacología , Supervivencia Celular , Clonación Molecular , ADN/biosíntesis , ADN/efectos de los fármacos , Desoxicitidina Monofosfato/análogos & derivados , Desoxicitidina Monofosfato/farmacología , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/farmacología , Técnica del Anticuerpo Fluorescente , Ganciclovir/farmacología , Neoplasias Hepáticas Experimentales/enzimología , Conteo por Cintilación , Simplexvirus/enzimología , Especificidad por Sustrato , Tritio , Células Tumorales Cultivadas/diagnóstico por imagen , Células Tumorales Cultivadas/efectos de los fármacos , Células Tumorales Cultivadas/enzimología , Proteínas ViralesRESUMEN
The determination of salivary drug concentrations is one of the major domains for the application of saliva in laboratory medicine. Its usefulness, however, has been criticized for many drugs because of the variability of the saliva/plasma concentration ratio (saliva/plasma ratio). Considering saliva as a model for transmembrane transport, drugs can be divided into 4 groups. The first group is characterized by a saliva/plasma ratio less than 1.0. In extreme cases a drug with negligible transport is either not detectable in saliva or is found in very low concentrations which are hard to measure or difficult to interpret. A second group leads to saliva/plasma ratios which are approximately constant and about 1.0 under most of the conditions studied. This group is ideal for monitoring salivary drug concentrations. A third group is sufficiently transferred into saliva, but the saliva/plasma ratio varies under different conditions. The reason for this variation is that the transport is influenced by several factors including an active transport mechanism. The varying influence of these factors on the saliva/plasma ratio largely depends on the physico-chemical characteristics of the particular substance. In a fourth group very high saliva/plasma ratios are observed primarily due to the degree of ionization of weak bases. A representative of each group is presented with its saliva/plasma ratio and its physico-chemical properties: ceftazidim, ethanol, digoxin and prilocain. In all cases the salivary concentration probably reflects the intracellular concentration in target tissues. All examples confirm saliva as an ideal in vivo model for the study of transmembrane transport in the human organism.
Asunto(s)
Anestésicos Locales/farmacocinética , Antibacterianos/farmacocinética , Digoxina/farmacocinética , Inhibidores Enzimáticos/farmacocinética , Drogas Ilícitas/farmacocinética , Saliva/química , Anestésicos Locales/sangre , Anestésicos Locales/metabolismo , Antibacterianos/sangre , Antibacterianos/metabolismo , Transporte Biológico Activo , Permeabilidad de la Membrana Celular , Digoxina/sangre , Digoxina/metabolismo , Relación Dosis-Respuesta a Droga , Monitoreo de Drogas , Inhibidores Enzimáticos/sangre , Inhibidores Enzimáticos/metabolismo , Humanos , Concentración de Iones de Hidrógeno , Drogas Ilícitas/sangre , Drogas Ilícitas/metabolismo , Unión Proteica , Saliva/metabolismoRESUMEN
The analytical performance of the Ciba Corning ACS:180 automated immunoassay system was studied according to a revised version of the ECCLS guidelines and partly according to a protocol of the Société Francaise de Biologie Clinique (SFBC) in a multicentre evaluation involving three laboratories. The determination of 8 analytes yielded more than 50,000 data. The values for imprecision showed that the ACS:180 is comparable to the ES-600, and gives better results for many analytes than other comparison methods. The recovery of system-assigned values in control sera was acceptable for all analytes. The upper limits of linearity claimed by the manufacturer were confirmed for all analytes. In many cases, the results for patients' samples showed good agreement between the ACS:180 and several different comparison methods. One exception was lutropin, with a large spread of the data. Furthermore, for human chorionic gonadotropin and prostate-specific antigen, the slopes of the fitting lines were significantly higher than 1. Triacylglycerols and haemoglobin did not significantly influence the measurements of any analyte. Bilirubin affected the measurement of triiodothyronine and human chorionic gonadotropin. Significant drift or carry-over effects were not detected. The selective ACS:180 is fully automatic, requires relative short personnel time, and was easy to operate.
Asunto(s)
Hormonas/sangre , Inmunoensayo/normas , Antígeno Prostático Específico/sangre , Autoanálisis , Estudios de Evaluación como Asunto , Femenino , Humanos , Inmunoensayo/métodos , Inmunoensayo/estadística & datos numéricos , Masculino , Valores de Referencia , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
Despite anatomical and biochemical similarities, salivary, sweat and lacrimal glandulas differ in their physiological functions. Salivary and tear fluid are required for the proper function of the epithelial layer from which they are secreted. The physiological function of sweat is the elimination of excess heat. The products of the three glandulas can be used to measure indicators either of glandula or of non-glandular diseases. In the latter case the indicator must be transported from the particular organ to the glandula where it is then secreted. In sweat, only one example has reached well accepted clinical importance. The measurement of electrolyte concentrations is the classical laboratory test for cystic fibrosis. The use of tears for diagnostic purposes has been proposed for drug monitoring, to verify the dry eye syndrome (Schirmer test), to detect lysosomal storage diseases (eg Morbus Gaucher) and hyperglycemia. The major domains for the application of saliva are hormone analyses (especially of steroids) and drug monitoring. Furthermore, the application of saliva has been proposed for the detection of several other analytes (eg secretory IgA, peptide hormones, HIV antibodies).
Asunto(s)
Saliva/química , Sudor/química , Lágrimas/química , Enfermedades de las Glándulas Suprarrenales/diagnóstico , Fibrosis Quística/diagnóstico , Electrólitos/análisis , Humanos , Enfermedades por Almacenamiento Lisosomal/diagnósticoRESUMEN
The analytical performance of the three analytical systems Reflotron, Ektachem DT60 and Seralyzer III was studied according to ECCLS guidelines (1) and partly according to a protocol of the Société Francaise de Biologie Clinique (SFBC) (2) in a multicentre evaluation involving four laboratories. The determination of 11 analytes led to more than 180,000 data. With the Ektachem DT60, imprecision was acceptable for all analytes except for sodium. With the Reflotron, imprecision for glucose and creatinine was wider than the acceptable limits. With the Seralyzer III, imprecision for glucose, uric acid, cholesterol, creatinine and potassium was not within acceptance limits. The recovery of system assigned control sera values was acceptable for all analytes, except for glucose, creatinine and sodium with the Ektachem DT60 system, and for all but glucose and cholesterol with the Reflotron. On the Seralyzer III, the limits of acceptance were exceeded only with the creatinine assay. The recovery of the reference method values with Kontrollogen L caused problems with all three systems and for all analytes. Only 30% of the mean values of Kontrollogen L measured with the Ektachem and with the Seralyzer III were within the limits of acceptance. 40% of the mean values determined with the Reflotron were inside these limits. The upper limits of linearity as claimed by the manufacturers were obtained with all analytes and systems with the exception of cholesterol on all systems and the creatinine assay on the Seralyzer III. The systems under test and several different comparison methods showed good agreement for the analysis of patient samples, except in one laboratory for the analysis of sodium and aspartate aminotransferase with the Ektachem system and potassium with the Seralyzer III. Turbidity showed no significant influence on the measurements of all analytes and all systems. Haemolysis, hyperproteinaemia, and bilirubinaemia affected several methods on all three systems. A start time delay of up to 60 s did not affect the results of the Reflotron, except in the case of the triacylglycerol assay, which was affected by start time delays greater than 45 s. The results of 4 assays on the Seralyzer III were decreased considerably by a delayed start time (triacylglycerols and creatinine above 5 s, aspartate aminotransferase above 35 s and creatine kinase above 15 s). For reliable results from all the assays in each of the three analytical systems, it was necessary to use the prescribed sample volume within certain limits. The practicability of all analytical systems tested was found to be very good. A field study was conducted with the Reflotron system. The analyte concentration was determined in venous blood from various patients. In 25 out of 30 experiments, the results of the "field" laboratories showed a greater spread about the fitting line than those obtained in the "expert" laboratories.
Asunto(s)
Química Clínica/métodos , Juego de Reactivos para Diagnóstico , Química Clínica/normas , Estabilidad de Medicamentos , Estudios de Evaluación como Asunto , Humanos , Tiras Reactivas , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Factores de TiempoRESUMEN
The salivary ethanol concentration correlates very well with the serum level (r = 0.98) in samples which are obtained almost simultaneously from persons undergoing a traffic control. If ethanol was referred to the aqueous compartment the saliva/plasma ratio was about 0.85; this ratio was about 11% less than the theoretical one and remained constant over the entire concentration range applied. Saliva could be taken together with breath samples from traffic participants which are controlled for ethanol consumption. The advantage of saliva in favour of blood is that it can be obtained nearly simultaneously with the breath sample without the intervention of a physician and does not hurt the person under suspicion. Furthermore saliva is suited for the voluntary surveillance of former alcoholics who are willing to prove that they are able to live abstinently.
Asunto(s)
Intoxicación Alcohólica/sangre , Etanol/farmacocinética , Saliva/metabolismo , Humanos , Reproducibilidad de los Resultados , Manejo de EspecímenesRESUMEN
A Working Group of the European Group for the Evaluation of Reagents and Analytical Systems in Laboratory Medicine proposes, after detailed study of the advantages and disadvantages of available strategies, the following quality specifications for analytical systems for clinical chemistry. Total imprecision should be: (a) less than one-half of the average within-subject biological variation, or (b) less than the state of the art achieved by the best 0.20 fractile of laboratories, whichever is the less stringent. The second approach may be used when data on biological variation do not exist. Inaccuracy should be: (a) less than one-quarter of the group (within- plus between-subject) biological variation, or (b) less than one-sixteenth of the reference interval, when data on group biological variation do not exist, or (c) less than twice the ideal imprecision, if the above specifications are too demanding.
Asunto(s)
Química Clínica/normas , Europa (Continente) , Humanos , Laboratorios , Control de CalidadRESUMEN
A multicentre evaluation of the blood gas-electrolyte-haematocrit-analyser BGE (Fa. Instrumentation Laboratory), following as far as possible the ECCLS guidelines for multicentre evaluation of blood gas analysers, was performed by three laboratories. The rules of the evaluation protocol were extended to the electrolyte and haematocrit determinations. The BGE proved to be easy to operate and maintain. The stability of the measuring system was good. The within-run imprecision of all electrodes was excellent. The same applies to the between-day imprecision, except for the calcium measurements. The systematic deviation of the gas electrodes was very small. Comparison studies revealed clinically significant deviations only for ionized calcium. Some suggestions for further improvements are made.
Asunto(s)
Análisis de los Gases de la Sangre/normas , Análisis de los Gases de la Sangre/métodos , Dióxido de Carbono/sangre , Electrólitos/sangre , Europa (Continente) , Alemania , Hematócrito , Humanos , Concentración de Iones de Hidrógeno , Laboratorios/normas , Oxígeno/sangreRESUMEN
The Clinical Chemistry Analyzer Dimension 380 manufactured by Du Pont de Nemours was tested in a multicentre evaluation according to the guide-lines of the European Committee for Clinical Laboratory Standards (ECCLS) and in part to the protocol of the Société Française de Biologie Clinique (SFBC). The instrument and the reagents were evaluated as a system, since both reagents and reagent cartridges are specifically designed for the instrument. Fourteen analytes including electrolytes, substrates and enzymes were tested. The evaluators summarized their experience as follows: 1. All parameters tested yield results comparable to established procedures. 2. Very good performance of the ion-selective-electrode unit. 3. The imprecision data of the system are, for most parameters, between 1 and 4% CV and thus equal to or better than those of the instruments compared. 4. No reagent or sample carry-over was detected after a minor modification of the instrument. 5. The linearity of Dimension test methods in general covers the range stated by the manufacturer. 6. Very good stability of the calibration curves (up to 2 months). 7. Good practicability of the whole system, including handling of reagents and a very user-friendly software.
Asunto(s)
Química Clínica/instrumentación , Análisis Químico de la Sangre/instrumentación , Europa (Continente) , Estudios de Evaluación como Asunto , HumanosRESUMEN
Captopril (CAS 62571-86-2) may be beneficial for the treatment of diabetes because of its activating effect on peripheral glucose consumption besides its well known blood pressure degradation. The glucose oxidation has been found to be activated by captopril in thrombocytes and mononuclear leucocytes, cell types which are usually considered to be independent from insulin. Because the oxidation of pyruvate labelled in position C-1 but not of 2-14C-pyruvate and of 1-14C-acetate was enhanced, captopril most probably stimulated the pyruvate decarboxylation reaction. The metabolism of glucose labelled in positions 1 and 6 was equally activated by captopril indicating another step which may be affected by captopril.