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Query: UMLS:C0020473 (hyperlipidemia)
 15,891 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The development of ion-selective electrodes (ISEs) for electrolyte measurements necessitates a re-evaluation of the biological and clinical interpretation of a result. In pathological situations (e.g., hyperlipidemia and hyperproteinemia) direct potentiometry is the method of choice for ion measurements in blood. However, the "plasma water effect" exists also in normal samples, requiring new reference values for physiological ranges. A compromise between medical and instrumentation workers retained the old reference values (flame photometry for Na+ and K+) by introducing correction factors into the ISE instruments, so that the results for direct ISE and flame photometry are the same for "normal" samples. Analyses of "abnormal" samples will reveal biases between the two methods. Now, a new generation of electrodes for assaying additional metabolites reopens the issue. Although classical methods measure a quantity of substance in a predetermined volume of sample, the majority of the substance is usually in the aqueous phase, and the volumes occupied by lipid and protein are not taken into consideration. In evaluating the NOVA 12 instrument (NOVA Biomedical), using electrodes for direct measurement in serum or plasma of Na, K, Cl, total CO2, urea, and glucose, we have demonstrated the inadequacy of classical measurements of urea and glucose, especially in pathological situations characterized by a large variation in the plasma water fraction.
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PMID:Electrode measurement of glucose and urea in undiluted samples. 220 6

A new instrument (NOVA 4 + 4) designed to measure serum chloride by ion-selective electrode (ISE)-direct potentiometry (without sample dilution) was evaluated and compared with two widely used methodologies for chloride determination. Mean values obtained with the Nova were significantly higher than those obtained by a colorimetric method and by coulometric titration. Unlike these procedures, which are performed after sample dilution, direct potentiometry was unaffected by changes in plasma water caused by hyperlipemia and/or high protein concentrations. The only important interference was falsely high choride caused by administered bromide or iodide. Therefore, the direct potentiometric method should be more accurate than the colorimetric or coulometric procedures, especially when plasma lipids or proteins are very high.
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PMID:Evaluation of the direct potentiometric method for serum chloride determination--comparison with the most commonly employed methodologies. 395 1