Journal of the International Federation of Clinical Chemistry最新文献

Immunoassay and other ligand assays have made a major impact on medical research and diagnosis since the first modern (radioisotopically-based) methods emerged. These ubiquitous microanalytic techniques are broadly classifiable as first generation (generally of "competitive" design, e.g., radioimmunoassay), and second generation (generally "noncompetitive," and relying on nonisotopic labels) these (often described as "ultrasensitive") being distinguished by dramatic improvements in sensitivity and performance time. A third generation is now in prospect (based on microarrays of antibody microspots) capable of ultrasensitive determination of hundreds of analytes in a drop of blood. Analogous technology (based on oligonucleotide arrays) is under intensive development for DNA analysis. Array technologies are likely to transform diagnostic medicine in the next decade.

Considerable advances have been made in our understanding of the genetics of primary immunodeficiencies over the last few years. The genetic defects underlying many forms of severe combined immunodeficiency, antibody deficiency, and neutrophil disorders are now known, raising the possibility of curative gene therapy for severe defects. These advances have also led to significant changes in our knowledge of basic mechanisms, not only of immunologic control but of cellular development and gene regulation.

Prostate-specific antigen (PSA) is the most important tumor marker for prostate cancer, although it is not a perfect marker as it is not cancer-specific. PSA, a member of the human kallikrein family, is present in two molecular forms in serum: free and complexed to protease inhibitors. PSA is now commonly measured on automated immunoassay systems employing monoclonal or polyclonal antibodies. Results from different assays can vary since some assays are not equimolar and react to the free and complexed forms differently. Utilization of the molecular forms of PSA is one approach to improve the sensitivity and specificity of the PSA assay. Patients with prostate cancer have a greater percentage of PSA bound to alpha1-antichymotripsin (ACT) than those without cancer. Measurement of the free to total PSA ratio in the diagnostic gray zone (usually 4-10 micrograms/liter of total PSA), where prostate cancer and benign prostatic hyperplasia (BPH) overlap, has been shown to eliminate between 16 and 79% of unnecessary biopsies. Free to total PSA cutoffs are influenced by the sensitivity and specificity values chosen, the reflex range for total PSA used, differences in free PSA assays, differences in populations studied, and factors such as total PSA concentrations, age, and prostate gland size. In addition to the molecular forms of PSA, age-specific reference ranges, rate of change of PSA concentrations (PSA velocity), ratio of serum PSA to prostate volume (PSA density), and neural network derived indices have been employed to improve the clinical utility of PSA measurements.

A number of reliable methods are currently available for the diagnosis of Helicobacter pylori infection. These diagnostic tests can be classified into invasive methods that require endoscopy and gastric biopsy, and noninvasive methods. Invasive methods include gastric mucosal biopsies at endoscopy for bacteriologic culture, histology, and the rapid urease test. Noninvasive methods include the urea breath test and serologic tests. Each of these diagnostic tests has its advantages and disadvantages. Histologic examination remains the gold standard for diagnosis. It can also detect coccoidal forms of the bacteria and be used to assess the severity of gastritis. Culture of H pylori should be performed if antibiotic sensitivity of the organism is required. A rapid urease test is the quickest test for H pylori status. The urea breath test detects urease activity in the entire stomach, thus eliminating the possibility of a sampling error, which occurs in random gastric biopsies. Serologic tests using either ELISA or latex-agglutination methods are excellent for diagnosis of H pylori infection, but not useful for monitoring effects of therapy. Recently, the polymerase chain reaction has been applied to fixed-tissue biopsies, as well as body secretions in the diagnosis of H pylori infection.

The objectives of the health reforms introduced in 1994 include universal coverage and cost containment. With these reforms, a new uniform for schedule and standards for laboratories have been introduced. The impact of these reforms is yet to be realized. It is predicted that with the imposition of new standards, many laboratories based in physicians' offices will disappear. Standards will also require more scientists and physicians trained in laboratory medicine.

Belatedly, automation is being introduced into hemostasis laboratories. Now, new analytic systems are also available for less specialized laboratories. New tests have been added as knowledge of the mechanisms of coagulation increases. This article will review the new technologies in coagulation testing and their diagnostic applications.

Total quality management (TQM) of laboratory services is connected with a comprehensive system of quality assurance, which integrates quality development, quality maintenance, and quality improvement. TQM concentrates not only on analytic performance and organizational issues, including specimen collection, reporting, and interpretation of results, but focuses also on the benefits to society related to the use of specific laboratory tests in prevention, early detection, and therapy monitoring, as well as on outcome measures. A prerequisite to TQM are international and national standardization programs for the establishment of optimized and standardized methods, as well as for the development and evaluation of suitable reference materials. Reference materials that have been or are being prepared, calibrated, and certified by international and national reference institutions will certainly contribute to the harmonization of results, with different test systems in hemostaseology, improving their quality and value.

Protein energy malnutrition (PEM) is widespread throughout the world in both community and hospital settings. Assessment of PEM in an individual consists of good dietary and clinical assessment, followed by laboratory measurements. Recent changes in body weight and simple anthropometric measurements are also useful. Laboratory measurements have the advantage in that they are independent of body size, they can be made precisely, and allow monitoring of progress. However, laboratory measurements must be interpreted with caution, especially in seriously ill patients in the hospital.

The essential role of glycohemoglobin measurements in diabetes care and the currently poor comparability of results between different methods used in clinical laboratories makes an international standardization absolutely necessary. The IFCC working group on HbA1c standardization is going to develop a reference system for the international standardization which is based on HbA1c as the biochemically well-defined major glycohemoglobin component, and consisting of primary and secondary reference materials, a reference method and adjusted reference and target values. The system will serve for the standardization of all glycohemoglobin assays.