Wiener klinische Wochenschrift. Supplementum最新文献

Requirements, possibilities, and pitfalls of electrolyte (sodium, potassium, and chloride) analysis are reviewed within the light of the experiences in the Academic Hospital St. Radboud, Nijmegen, The Netherlands. In view of the ever increasing demands on short turnaround times, attention is paid to problems with specimen delivery, instrumentation and data distribution. The precision levels of available alternatives for electrolyte analysis namely: flame photometry, direct and indirect ion selective electrode methods, dry chemistry, and the newly developed enzymatic approach for sodium and potassium analysis are discussed.

The overall reliability of measuring digoxin in serum improved significantly with the discovery and application of immunoassays. However, because of the low concentration of digoxin being measured, its narrow therapeutic range in serum, and the presence of endogenous digoxin-like immunoreactive factors (DLIF), developing assays for measuring digoxin still pose formidable challenges. In this presentation, recent developments in the characterization of DLIF from bovine adrenal cortex and human serum are described. Data accumulated to date suggest there is one principal endogenous molecular factor (DLIF) in humans that cross-reacts with anti-digoxin antibodies. This factor exists at sufficiently high concentrations in some patients to interfere with measurements of digoxin by most digoxin immunoassays. All digoxin immunoassays should be tested to interference from this endogenous factor. Various techniques for reducing DLIF cross-reactivity are reviewed. The isolation and purification of DLIF now provides new approaches for selecting specific anti-digoxin antibodies used in developing more accurate digoxin immunoassays.

Sera from the routine of therapeutic drug monitoring were assayed for phenobarbital, phenytoin, and theophylline with three different methods: fluorescence polarization immunoassay as the standard procedure, the new CEDIA assays within a multicenter evaluation and HPLC which is known to yield results with a high specificity. CVs for between-day imprecision ranged from 2.6-8.6%, depending on the concentration of the drugs. There was a tendency to lower CVs for the HPLC procedure. Accuracy was verified with commercial control materials and spiked sera and proved to be satisfactory for all three methods and parameters. The linear range was approx. twice as wide for the HPLC compared with the other methods. The method comparisons were quite favorable. Deviations occurred mainly in the subtherapeutic concentration range.

New analytical methods have to be considered also with respect to their economic efficiency. Here we present the application of an economic analysis based on the rules of applied economics in our institute for clinical chemistry and laboratory medicine. We started with an analysis of laboratory structure and economic efficiency in 1988, which since then has been followed by a continuously performed laboratory controlling system. The results of unit costing show the different cost groups, which add up to the cost of a single electrolyte determination. Regarding the transferability of our data to other laboratories, one has to consider that the main cost groups besides personnel cost are the apportionment of the overhead cost and the depreciation cost; both may vary markedly between each laboratory. Variable cost (reagents and consumables) differ widely from flame photometry to enzymatic electrolyte determination, but they amount only to 3-15% of the total cost.

Therapeutic and toxic actions of cardiac glycosides are attributed to an inhibition of Na, K-ATPase. The therapeutically relevant range is between 25% and 50% inhibition. There is a good correlation between the average steady state serum concentration of glycosides and their therapeutic action. However, therapeutic and toxic effects set in with a latency and therefore do not follow the daily variations in glycoside concentration. Although the effect follows the average serum concentrations, only the minimal concentration is measured. In principle this is only adequate if the ratio of average/minimal concentration is constant. A model calculation showed that with a constant average steady state concentration an increase in the distribution volume or a decrease in total body clearance with corresponding reduction of the daily dose lead to an increase of the minimal concentrations of 5-7%. This means a corresponding underestimation of the average concentration from the minimum concentration. However, the deviations are too small to be of clinical relevance.

Acute polyradiculitis ("acute inflammatory demyelinating polyradiculitis--AIDP" or the Landry-Guillain-Barré syndrome--GBS) is an acute inflammatory disease of the peripheral nervous system. Despite extremely severe courses and complications, the prognosis is favourable for the majority of patients. The typical clinical course is featured by non-characteristic sensory symptoms following an infection, with ensuing ascending motor signs and symptoms which, in 80% of the patients, reach a maximum within two weeks. The legs are usually involved before the arms. About 50% of the patients show involvement of cranial nerves. In the acute phase, respiratory insufficiency and autonomous dysfunctions may occur. For diagnosis, predominantly clinical criteria are used according to the criteria summarized by Asbury.

A new colorimetric test for kinetic determination of beta-N-acetylglucosaminidase activity in urine is evaluated according to the diagnostic usefulness in patients after kidney transplantation and in workers exposed to cadmium. The new test is suited to monitor renal parenchymal alterations.