Multicenter evaluation of a new immunoassay for procalcitonin measurement on the Kryptor System.

We compared the manually performed LUMItest procalcitonin (PCT) assay with the newly developed fully mechanized Kryptor PCT assay and determined the essential assay characteristics of this assay. The new Kryptor PCT assay was evaluated according to modified NCCLS EP-10/EP-6 protocols in five different laboratories. Samples from 696 patients were assayed using the original LUMItest PCT assay and the new Kryptor PCT assay. Possible interference by hemoglobin, triglycerides and bilirubin was evaluated by spiking patient plasma with the appropriate substances. The functional assay sensitivity (FAS) was determined by analyzing samples with low PCT concentrations. The FAS of the new Kryptor PCT assay was 0.04 ng/ml and the imprecision within- and between-series below 5% and below 10%, respectively. Within the smallest range of determination, from 0.3 ng/ml to 50 ng/ml, common to the LUMItest PCT assay (x) and the Kryptor PCT assay (y) the values correlated well: y=0.64+0.94x, s.xy=2.78 ng/ml. The performance characteristics of the Kryptor PCT assay are fully compatible with the intended clinical use. The assay allows determination of PCT in a turnaround time (TAT) of about 20 minutes and thus is adequate for STAT analyses.

IFCC recommendation on reporting results for blood glucose.

In human beings, glucose is distributed like water between erythrocytes and plasma. The molality of glucose (amount of glucose per unit water mass) is the same throughout the sample. Different water concentrations in calibrator, plasma, and erythrocyte fluid can explain some differences that are dependent on sample type, methods requiring sample dilution, and direct reading biosensors detecting molality. Different devices for the measurement of glucose detect and report fundamentally different analytical quantities. The differences exceed the maximum allowable error of glucose determinations for diagnosing and monitoring diabetes mellitus, and they complicate the treatment. The goal of the International Federation of Clinical Chemistry, Scientific Division, Working Group on Selective Electrodes (IFCC-SD WGSE) is to reach a global consensus on reporting results. The document recommends harmonizing to the concentration of glucose in plasma (with the unit mmol/l), irrespective of sample type or technology. A constant factor of 1.11 will convert measured concentration in whole blood to the equivalent concentration in plasma.

High-temperature solid-phase microextraction procedure for the detection of drugs by gas chromatography-mass spectrometry.

High-temperature headspace solid-phase microextraction (SPME) with simultaneous ("in situ") derivatisation (acetylation or silylation) is a new sample preparation technique for the screening of illicit drugs in urine and for the confirmation analysis in serum by GC-MS. After extraction of urine with a small portion of an organic solvent mixture (e.g., 2 ml of hexane-ethyl acetate) at pH 9, the organic layer is separated and evaporated to dryness in a small headspace vial. A SPME-fiber (e.g., polyacrylate) doped with acetic anhydride-pyridine (for acetylation) is exposed to the vapour phase for 10 min at 200 degrees C in a blockheater. The SPME fiber is then injected into the GC-MS for thermal desorption and analysis. After addition of perchloric acid and extraction with n-hexane to remove lipids, the serum can be analysed after adjusting to pH 9 as described for urine. Very clean extracts are obtained. The various drugs investigated could be detected and identified in urine by the total ion current technique at the following concentrations: amphetamines (200 microg/l), barbiturates (500 microg/l), benzodiazepines (100 microg/l), benzoylecgonine (150 microg/l), methadone (100 microg/l) and opiates (200 microg/l). In serum all drugs could be detected by the selected ion monitoring technique within their therapeutic range. As compared to liquid-liquid extraction only small amounts of organic solvent are needed and larger amounts of the pertinent analytes could be transferred to the GC column. In contrast to solid-phase extraction (SPE), the SPME-fiber is reusable several times (as there is no contamination by endogenous compounds). The method is time-saving and can be mechanised by the use of a dedicated autosampler.

Use of ion-selective electrodes for blood-electrolyte analysis. Recommendations for nomenclature, definitions and conventions. International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). Scientific Division Working Group on Selective Electrodes.

This paper will familiarize the reader with the terms used to describe the behavior of ion-selective electrodes, particularly in relation to their use in clinical chemistry for determination of blood electrolyte cations. It serves as an introduction to a series of papers dealing with important cations in blood, namely calcium, sodium, and potassium. The detailed relationships between the ion activity determined by means of ion-selective electrode potentiometry in undiluted specimens, and the total substance concentration measured by flame atomic-emission spectrometry are described by flow chart and equations. Adoption of a convention for reporting results is recommended. The Working Group on Selective Electrodes has taken into account recent revisions of IUPAC recommendations on nomenclature and selectivity coefficient determinations for ion-selective electrodes, and benefited from the experience of a member of the WG, who was also involved in the IUPAC discussions. Nomenclature for determined quantities follows previous IUPAC/IFCC joint recommendations.

Procalcitonin in fever of unknown origin after liver transplantation: a variable to differentiate acute rejection from infection.

OBJECTIVE: Does procalcitonin (PCT) differentiate between infection and rejection after liver transplantation in patients with fever of unknown origin? DESIGN: Open prospective trial. SETTING: Transplant intensive care unit at a university hospital. PATIENTS: Forty patients after liver transplantation. INTERVENTIONS: Liver biopsy for the diagnosis of rejection and transcutaneous aspiration cytology for monitoring of lymphocyte activation. MEASUREMENTS: Procalcitonin from EDTA plasma, Acute Physiology and Chronic Health Evaluation II, and sepsis score. RESULTS: Eleven patients experienced an infectious complication resulting in an increase in PCT concentrations (2.2-41.7 ng/mL). Eleven patients had a rejection episode; none of these patients showed a rise in PCT concentrations. The statistical difference between PCT concentrations in rejection and infection was significant (p<.05) on the day of diagnosis. CONCLUSION: PCT allows for differentiation between rejection and infection in patients with fever of unknown origin. Elevation of PCT plasma concentrations develops early postoperatively from operation trauma, and in the case of fever of unknown origin, with no rise in PCT, a rejection may be suspected.

IFCC recommended reference method for the determination of the substance concentration of ionized calcium in undiluted serum, plasma or whole blood.

A reference method is described for the determination of the substance concentration of ionized calcium in plasma by which ionized calcium (free or unbound) may be reliably determined on the basis of calibration with aqueous solutions with known concentration of ionized calcium. The composition of the calibration solutions is chosen such that the activity coefficient of the calcium ion is assumed to be identical both in the calibration solutions and in "normal" plasma, i.e. by convention, the ionic strength (Im) is 0.160 mol/kg. The convention is adopted of reporting ionized calcium measurements as concentration expressed as mmol/l. The proposed reference method for ionized calcium measurement in plasma is based on the use of a cell consisting of an external reference electrode with a saturated potassium chloride liquid/liquid junction in combination with a calcium ion-selective membrane electrode of defined construction and performance. Procedures for using the reference cell and a protocol for sample measurement are described. The preparation of the calibration solutions to be used are described in detail in Appendix A, secondary calibration solutions and check standards in Appendix B, and reference cell vessel design in Appendix C.

Recommendations for measurement of and conventions for reporting sodium and potassium by ion-selective electrodes in undiluted serum, plasma or whole blood. International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). IFCC Scientific Division Working Group on Selective Electrodes.

Ion-selective electrodes (ISEs) respond to ion-activity and therefore do not sense substance concentration directly. However, it is recognized that sodium and potassium in plasma will continue to be expressed for clinical purposes in terms of substance concentration (mmol/l). A convention is proposed whereby for routine clinical purposes results of ISE measurements of sodium and potassium in undiluted plasma should be reported in terms of substance concentration (mmol/l). In specimens with normal concentrations of plasma water, total CO2, lipids, protein and pH, the values will concur with the total substance concentration as determined for example by flame atomic emission spectrometry (FAES) or ISE measurements on diluted samples. In specimens with abnormal concentrations of plasma water, the results will differ. However, under these circumstances, measurements of sodium and potassium by ISE in the undiluted sample will more appropriately reflect the activity of sodium and potassium and are therefore clinically more relevant than the determination in diluted samples. Detailed recommendations are made about practical procedures to achieve this. The recommended name for this quantity is the substance concentration of ionized sodium or ionized potassium in plasma, as opposed to total sodium or total potassium determined by, e.g. FAES, or ISE measurements on diluted samples.

[Diagnosing magnesium deficiency. Current recommendations of the Society for Magnesium Research]. / Diagnostikdes Magnesiummangels. Aktuelle Empfehlungen der Gesellschaft für Magnesium-forschung e. V.

The cardiovascular risk increases with decreasing serum levels of magnesium, and this already at concentrations within the previous reference range (0.70-1.10 mmol/L). For this reason, the Society for Magnesium Research has updated its 1986 recommendations for the diagnosis of magnesium deficiency. The diagnosis is based on the patient's history, his clinical symptoms, and the results of clinical-chemical investigations of plasma/serum and urine. Further diagnostic methods used include the determination of ionized serum magnesium and the magnesium retention test. The optimal serum magnesium concentration is > 0.80 mmol/L.

Procalcitonin-a new diagnostic tool in complications following liver transplantation.

OBJECTIVE: Does procalcitonin (PCT) allow differentiation between infection and rejection following liver transplantation in the case of fever of unknown origin (FUO)? DESIGN: Open prospective trial. SETTING: transplant intensive care unit at a university hospital. PATIENTS: Forty patients after liver transplantation. INTERVENTIONS: Liver biopsy for diagnosis of rejection, transcutaneous aspiration cytology for monitoring of lymphocyte activation. MEASUREMENTS: Procalcitonin from EDTA plasma, APACHE II, Sepsis, score (Elbute and Stoner). RESULTS: Eleven patients suffered an infectious complication resulting in an increase in PCT levels (2.2-41.7 ng/ml). Eleven patients developed a rejection episode; none of these patients showed a rise in PCT levels. The statistical difference between PCT levels in rejection and infection was significant (p<0.05) on the day of diagnosis. CONCLUSION: PCT allows differentiation between rejection and infection in the case of FUO. Elevation of PCT plasma levels develops early postoperatively due to operation trauma, and, in the case of FUO with no rise in PCT, a rejection may be suspected.

Portable blood gas and electrolyte analyzer evaluated in a multiinstitutional study.

A recently introduced blood gas/electrolyte analyzer (SenDx 100((R)), renamed ABL70) intended for point-of-care, near-patient, or stat laboratory use was evaluated simultaneously in four different institutions and compared with three different laboratory bench analyzers with respect to imprecision, inaccuracy (assessed by tonometry), and patient-sample analyses. The analyzer is equipped with a sensor cassette and a reagent cartridge for 50, 100, or 200 analyses and 100 or more traditional quality-control measurements. One analysis requires 170 microL of whole blood and takes <90 s. Statistically, the instrument performed somewhat better (lower CVs) for PO2 and potassium and somewhat worse for pH, PCO2, and ionized calcium than the respective comparison analyzers. However, the overall performance (in terms of CV and accuracy) was satisfactory in terms of clinical (e.g., CLIA '88) goals in all institutions. The mean difference and the CV of that difference in some 400 patient-sample comparisons were as follows: 0.010 (+/- 0.002%) for pH, -0.65 mmHg (+/- 4%) for PCO2, -0.49 mmHg (+/- 6%) for Po2, 0.44 mmol/L (+/- 1.2%) for sodium, -0.013 mmol/L (+/- 2.9%) for potassium, -0.016 mmol/L (+/- 2.6%) for ionized calcium, and -0.016 L/L (+/- 7. 1%) for the hematocrit. Its acceptable analytical performance and ease of operation make the SenDx 100 suitable for the analysis of blood gases and electrolytes.

International Federation of Clinical Chemistry (IFCC). Recommendation on mean molar activity coefficients and single ion activity coefficients of solutions for calibration of ion-selective electrodes for sodium, potassium and calcium determination.

In principle, flame photometry measures substance concentration, and ion-selective electrodes (ISEs) measure ion activity. However, the situation regarding the comparison of results from the two techniques when applied to blood plasma is complex. The problem can be approached experimentally from the point of view of calibration of ion-selective electrodes with concentration calibrators, and similar procedures are adopted for commercial ISE-based clinical analysers. Nevertheless, there is interest in the evaluation of single ion activities in blood plasma and solutions simulating its ionic composition. Solutions are proposed for calibrating ion-selective electrodes for the determination of sodium, potassium and calcium. It is recommended that the values for single ion activities derived from the Pitzer treatment of mixed electrolyte solutions be adopted, because, although this has some empirical features, it has a sounder theoretical basis than the previously used Stokes-Robinson-Bates hydration approach.

Ionised and total magnesium serum concentrations in renal and hepatic diseases.

Ionised and total magnesium concentrations were determined in the serum of different groups of patients suffering from renal or hepatic diseases. Ionised magnesium was measured by Microlyte 6 (KONE, Espoo, Finland) and total magnesium by atomic absorption spectrometry. In renal insufficiency ionised and total magnesium concentrations were almost equally increased. In proteinuria with a normal glomerular filtration rate, "pseudohypomàgnesaemia" was observed, i.e. decreased total magnesium concentration in parallel with a decreased albumin concentration with no significant change in the concentration of ionised magnesium. Hypermagnesaemia occurred in liver diseases combined with renal insufficiency, whereas "pseudohypomagnesaemia" was most often found in the absence of renal failure. Also treatment with an aldosterone antagonist was associated with a normal ionised magnesium concentration, but the total magnesium concentration was decreased; when additional magnesium was administered, the total magnesium concentration approached a normal value, while ionised magnesium slightly exceeded reference values. Only during cyclosporin treatment did both ionised and total magnesium concentrations become lowered. However, the decrease of total magnesium exceeded that of ionised magnesium due to concomitant hypoalbuminaemia with reduction of the protein-bound fraction. It is concluded that especially low total magnesium concentrations should be investigated by measurement of ionised magnesium to exclude "pseudohypomagnesaemia".

International consensus on the standardization of sodium and potassium measurements by ion-selective electrodes in undiluted samples.

The International Federation of Clinical Chemistry (IFCC) and the National Committee for Clinical Laboratory Standards (NCCLS) are about to recommend to adjust sodium and potassium measurements by ion-selective electrodes in undiluted samples to the amount of substance concentration in the sample as determined, e.g., by flame atomic emission spectrometry. The adjustment is only valid in case of normal standardized sera (or plasma), implying "normal" water concentration (normal concentration of proteins, lipids or other macromolecules), "normal" binding of the pertinent electrolytes and "normal" coefficient of activity. If these criteria are not met, results obtained by "adjusted" ISE's will differ from total molar concentration. That is: in individual samples of patients results from ISE's and total molar concentration will differ unpredictably. It forced IFCC to propose new quantities for the measurements by adjusted ISE's: ionized sodium and ionized potassium. The reference interval for ionized sodium and ionized potassium is identical to the pertinent reference interval for molar concentration of total sodium and total potassium, but it is in contrast independent from water concentration and valid, e.g., in hypoproteinaemia as well as in hyperlipaemia or hyperproteinaemia. Accuracy control of ionized sodium and ionized potassium based on reference method values is hampered by abnormal water concentration and inadequate properties of the matrix of many control sera. Alternative approaches how to report measurements by ISE's in undiluted samples, such as activity or free molal concentration are discussed with their pros and cons regarding accuracy control by reference method values. The need for appropriate control materials with a matrix similar to native human sera is stressed.

Ionized magnesium concentration during liver transplantation, resection of the liver and cardiac surgery.

In this study we investigated three groups of patients, the first undergoing liver transplantation (n = 9), the second resection of the liver (n = 7) and the third cardiac surgery (n = 10) with regard to changes of ionized and total magnesium concentration during operation. Liver transplantation: Ionized magnesium concentration decreased from 0.58 mmol/L to 0.34 mmol/L far below the reference interval (0.49-0.72 mmol/L), whereas total magnesium concentration changed only from 0.78 mmol/L to 0.67 mmol/L (reference interval: 0.65-1.05 mmol/L). Citrate concentration increased from 220 mumol/L to 1925 mumol/L (anhepatic stage) because of massive transfusion of blood products. It was inversely correlated to ionized magnesium concentration. Resection of the liver: There was a decline of ionized magnesium from 0.56 mmol/L to 0.43 mmol/L, which slightly exceeded the decline of total magnesium from 0.74 mmol/L to 0.64 mmol/L. Citrate concentration increased moderately even in cases, when no citrate was administered reflecting reduced hepatic function during operation. Cardiac surgery: Only in patients, to whom citrate but not magnesium was infused, ionized magnesium concentration fell slightly below the reference interval (0.45 mmol/L). In the other patients, to whom magnesium was administered, ionized magnesium concentration was within the reference interval or exceeded it. It is concluded that in patients with impaired hepatic function and/or high citrate load the monitoring of ionized magnesium concentration is mandatory.

Relationship between ionized and total magnesium in serum.

The relationship between the concentration of ionized magnesium and total magnesium was investigated. Ionized magnesium was determined by an ion-selective electrode (Microlyte 6, KONE) and the result was adjusted to pH 7.4. Total magnesium concentration was measured by flame atomic absorption spectrometry. Total and ionized magnesium were only closely related in marked hypermagnesaemia (> 1.2 mmol/L), but correlation was poor in samples with slightly elevated total concentration or in hypomagnesaemia (< 0.65 mmol/L). The relationship was dependent on protein concentration. The agreement between total and ionized magnesium was acceptable in normoproteinaemia, but in hypoproteinaemia (< 40 g/L) total magnesium concentration was classified in 35% of the samples as below or within the reference interval, whereas the pertinent ionized magnesium concentration was normal or elevated, instead. Studies on paraproteinaemic sera clearly demonstrated that albumin concentration is most important for the size of the protein bound fraction.

International Federation of Clinical Chemistry (IFCC), Committee on pH, Blood Gases and Electrolytes: approved IFCC recommendation on definitions of quantities and conventions related to blood gases and pH.

Terminology in blood pH and gas analysis can be confusing, both because more than one name has been used for the same quantity, and because the same name has been used for more than one quantity. In addition, several calculated quantities are commonly used, but in some cases many different algorithms have been published for a single quantity. This document contains definitions of the most useful quantities in blood pH and gas analysis, and presents algorithms for the most useful calculated quantities. Use of these should lessen confusion among users and should also result in data that are more comparable among laboratories.

International Federation of Clinical Chemistry (IFCC). Scientific Division. Committee on pH, Blood Gases and Electrolytes. Approved IFCC recommendations on whole blood sampling, transport and storage for simultaneous determination of pH, blood gases and electrolytes.

Pre-analytical variables, e.g., specimen collection, transport, and storage, can contribute significantly to inaccurate pH, blood gas, and electrolyte values. The International Federation of Clinical Chemistry (IFCC), through its Committee on pH, Blood Gases and Electrolytes, has developed specific recommendations to minimize the undesirable effects of pre-analytical variables. The Committee has drawn upon the experiences of its own members as well as published data by others. Specifically, the Committee has included pertinent guidelines and suggestions by the IFCC Working Group on Selective Electrodes (WGSE), the National Committee on Clinical Laboratory Standards (NCCLS), and the Electrolyte/Blood Gas Division of the American Association for Clinical Chemistry (AACC). This paper will familiarize the reader with the effect of different types of specimen containers and anticoagulants. It discusses important aspects of specimen collection procedures including patients status and special precautions during specimen collection from indwelling catheters or cannulae. The paper also identifies different requirements in storage and transport of specimens for blood gas and electrolyte analysis.

Estimation of ifosfamide/cisplatinum-induced renal toxicity by urinary protein analysis.

Ifosfamide (IFO) chemotherapy has been reported to result in deToni-Debré-Fanconi syndrome in a minority of patients only, but evaluation of tubular transport capacities has identified a substantial number of patients as having subclinical tubular dysfunction. After completion of combination chemotherapy employing IFO (n = 37) or IFO plus cisplatinum (CPL) (n = 27), glomerular and tubular function was assessed in 64 patients by the urinary excretion of transferrin, IgG, albumin, alpha 1-microglobulin (A1M) and N-acetyl-beta-D-glucosaminidase. Sodium dodecyl sulphate polyacrylamide gel electrophoresis was performed in 21 patients. The determination of urinary marker proteins was compared with the glomerular filtration rate, the fractional phosphate and percent amino acid reabsorption. A reduced glomerular filtration rate was observed in 9.8% of patients. Tubular dysfunction was frequent, with a predominance of renal amino acid (57%) and A1M (48%) loss. IFO-mediated renal toxicity was dose dependent. CPL treatment resulted in significant enhancement of tubular toxicity induced by IFO, whereas concomitant gentamicin therapy did not affect tubular function. Measurement of urinary protein cannot replace other tests for tubular dysfunction in IFO-treated patients, because the spectrum of IFO-induced nephrotoxicity includes dysfunction of different and independent transport mechanisms of the proximal tubular system. Increased urinary A1M excretion is an important indicator of impaired tubular protein reabsorption.

Pulse amplitude and frequency modulation of parathyroid hormone in early postmenopausal women before and on hormone replacement therapy.

Although the pathophysiology of postmenopausal osteoporosis has been investigated extensively, it is still not established in what respect PTH is related to the events. Recently, consistent data on the pulsatile secretion of PTH in man have been published. In this study intact PTH was measured in six early postmenopausal women before and after 6 months of hormone replacement therapy (HRT; 0.6 mg conjugated estrogens and 5 mg medrogestone). In addition to parameters of calcium metabolism and bone mass and to control HRT, intact PTH was measured in blood drawn over 6 h every 2 min. With HRT there was a 30% reduction in PTH secretion. Both the amount secreted per pulse (baseline, 26.8 +/- 6.9 ng/L; HRT, 21.4 +/- 7.6 ng/L; P < 0.05) as well as the basal secretion (baseline, 232.6 +/- 117.6 ng/L.h; HRT, 145.5 +/- 80.0 ng/L.h; P < 0.01) were reduced, whereas the pulse count per h remained constant (baseline, 5.1 +/- 2.2; HRT, 5.1 +/- 1.3). Power spectrum analysis showed a shift in spectral maxima consistent with these findings. Ionized and total calcium were slightly, but nonsignificantly, reduced with treatment. In summary we conclude that in early postmenopausal women, HRT reduces the secretion of PTH by reducing both the basal secretion and the amount secreted per pulse. It is conceivable that some of the known effects of HRT on bone metabolism might be mediated by the modulation of PTH secretion.