Chemistry and Laboratory Medicine

The boundaries between clinical chemistry and other areas of laboratory medicine are not always distinct. In many institutions, clinical chemists initiate and direct activities, such as laboratory informatics and POCT. In some areas of the world, the term clinical chemistry has long been used to include laboratory areas such as hemostasis, thrombosis testing, immunology testing, and parts of hematology that in the United States are not considered to be part of classical clinical chemistry. 

The close associations of cfinical chemistry and laboratory medicine have been evident in other public ways. Most journals in the field of clinical chemistry publish papers in all of the areas of laboratory medicine. The subtitle of the journal Clinical Chemistry even includes the term Laboratory Medicine. Moreover, the international association of clinical chemistry societies is now called the International Federation of Cfinical Chemistry and Laboratory Medicine. 

---

Institute of Clinical Chemistry and Laboratory Medicine, University of Regensburg, Regensburg Germany... 

The properties of a pH electrode are characterized by parameters like linear response slope, response time, sensitivity, selectivity, reproducibility/accuracy, stability and biocompatibility. Most of these properties are related to each other, and an optimization process of sensor properties often leads to a compromised result. For the development of pH sensors for in-vivo measurements or implantable applications, both reproducibility and biocompatibility are crucial. Recommendations about using ion-selective electrodes for blood electrolyte analysis have been made by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) [37], IUPAC working party on pH has published IUPAC s recommendations on the definition, standards, and procedures... 

Wang, J., Electroanalytical Techniques in Clinical Chemistry and Laboratory Medicine, VCH, New York, 1988. A short book from the master himself. Not an easy read, though, as it seems to presuppose quite a lot of background material - but it is, after all, applied electroanalysis, as the title suggests. The chapter on ion-selective electrodes is dated in content but full of useful insights. 

Cunningham D, Young D. Measurements of glucose on the skin surface, in stratum comeum and in transcutaneous extracts implications for physiological sampling. Clinical Chemistry and Laboratory Medicine 2003, 41, 1224-1228. 

Heise HM, Bittner A, Marback R. Near-infrared reflectance spectroscopy for noninvasive monitoring of metabolites. Clinical Chemistry and Laboratory Medicine 2000, 38, 137-145. 

It is relevant to ask how often the routine measurement procedures currently used in laboratory medicine provide results that are traceable to high-level calibrators and reference measurement procedures (Lequin personal communication). It turns out that primary reference measurement procedures and primary calibrators are only available for about 30 types of quantity such as blood plasma concentration of bilirubins, cholesterols and sodium ion. International reference measurement procedures from the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) and corresponding certified reference material from BCR are available for the catalytic activity concentration of a few enzymes such as alkaline phosphatase and creatine kinase in plasma. For another 25 types of quantity, such... 

With the introduction of quality assurance in the diagnostic laboratory 56 years ago [6], a kind of educational and benchmarking process started forcing laboratories, national and international organizations, and the IVD industry to improve the methods applied in clinical laboratories. Comparison of the measurements of enzyme activity demonstrate that the analytical performance of the methods applied 30 years ago were far beyond the biological variation and most probably insufficient for medical needs. Interlaboratory comparisons show that with the new routine methods based on recommendations of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) (Table 5) comparable results can be obtained irrespective of time and space and thus small individual variations can now be detected. Similar improvements in the analytical process in clinical laboratories can be reported generally for homogenous measurands. 

Nevertheless, manufacturers are interested in the further development of reference materials and reference measurement procedures suited for application in human serum for medical purposes. Therefore, industry appreciates the efforts started by the Joint Committee of Trace-ability and Laboratory Medicine (JCTLM), an initiative supported by the Bureau International des Poids et Mesures (BIPM) and the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) in order to develop suitable reference materials and measurement procedures, as well as to collect information on the activities of reference laboratories. In view of the limited resources and large efforts connected with these activities, clear priorities need to be set. Projects need to take into account the clinical importance of the analyte, consider the technical difficulties that must be overcome, and, most importantly, decide whether improvement of the metrological side is reflected in a gain of medically relevant information. 

R. A. Felder, Third Symposium on Automation, Robotics and Artificial Intelligence Applied to Analytical Chemistry and Laboratory Medicine, Based on a conference held in San Diego, CA, 15-18 January 1994, in Chemom. Intell. Lab. Syst., 26 (2), Elsevier, Amsterdam, The Netherlands, 1994. 

R. Schafer, C. Schulz and O. Stuckert, 4th International conference on automation, robotics and artificial intelligence applied to analytical chemistry and laboratory medicine, Montreux, Feb, (1995). 

The international unit itself may eventually be replaced by the SI unit termed the katal, the SI derived unit for catalytic activity (see Chapter 1). It is defined as moles per second. The name katal had been used for this unit for decades, but did not become an official SI derived unit until 1999 with Resolution 12 of the 21st CGPM, on the recommendation of the International Federation of Cfinical chemistry and Laboratory Medicine. Both the International Union of Pure and Applied Chemistry and the lUB now recommend that enzyme activity be expressed in moles per second and that the enzyme concentration be expressed in terms of katals per liter (kat/L). Thus, lU = lO mol/fiOs = 16.7 X 10 mol/s, or l.Onkat/L - 0.06U/L. The formal adoption of the katal is hoped to discourage the use of a non-SI unit called unit, symbol U, defined as micromoles per minute. Units are more commonly used than the katal in practice at present, but their definition lacks coherence with the SI system. 

Schumann G, Bonora R, Ceriotti F, Ferard G, Ferrero CA, et al. IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 C. International Federation of Clinical Chemistry and Laboratory Medicine. Part 4. Reference procedure for the measurement of catalytic concentration of alanine aminotransferase. Clin Chem Lab Med 2002 40 718-24. 

Clinical Chemistry, Laboratory Medicine, and Evidence-Based Laboratory Medicine In this chapter, we review the new influences on clinical chemistry and laboratory medicine from the fields of cfinical epidemiology and evidence-based medicine (EBM). Cfinical epidemiologists have developed study designs to quantify the diagnostic accuracy of the tests developed in laboratory medicine, and study methods to evaluate the effect and value of laboratory testing in healthcare. Practitioners of EBM focus on use of the best available evidence from such well-designed studies in the care of individual patients. EBM rephrases problems in the clinical care of patients as structured clinical questions, looks for the available evidence, evaluates the quality of cfinical studies, evaluates the clinical implications of the results, and provides tools to help clinicians optimally use those results in the care of individual patients. 

Lumbreras-Lacarra B, Ramos-Rinc6n JM, Hernandez-Aguado I. Methodology in diagnostic laboratory test research in Clinical Chemistry and Clinical Chemistry and Laboratory Medicine. Clin Chem 2004 50 530-6. 

The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) recommends the term reference values and related terms, such as reference individual, reference limit, reference interval, and observed values. The definitions given below and the presentation in the following sections of this chapter are in accordance with the IFCC recommendations. ... 

The ATP produced is measured by hexokinase (HK)/ glucose-6-phosphate dehydrogenase (G6PD) coupled reactions that ultimately convert NADP to NADPH, which is monitored spectrophotometricaUy. Oliver first reported this method that RosaUd also described with the improvement of adding AMP to inhibit adenylate kinase (AK) and cysteine to activate CK. Subsequently, Szasz and colleagues optimized the assay by adding N-acetylcysteine to activate CK, EDTA to bind Ca and to increase the stability of the reaction mixture, and adenosine pentaphosphate (ApsA) in addition to AMP to inhibit AK. A reference method based on this previous experience was developed by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) it was modified recently to produce a reference procedure for the measurement of CK at 37 °C. ... 

For many years, much attention has been focused on certain lipids and the lipoproteins that transport them in the circulation, mainly because of their strong association with coronary heart disease (CHD). Therefore the use of the term lipids in chnical chemistry and laboratory medicine has become virtually synonymous with lipoprotein metabolism... 

Plasma lipid and lipoprotein concentrations in male and female subjects are presented in Tables 26-7 through 26-10. These reference intervals have been developed using the Lipid Research CHnics (LRC) population. Although reference intervals for apo A-I and B-lOO from the Framingham Heart Study using the approved World Health Organiza-tion/Internationai Federation of Clinical Chemistry and Laboratory Medicine (IFCC) calibrators have been published,distributions of these two proteins that better reflect the North American population have only recently... 

Marcovina SM, Albers JJ, Scanu AM, Kennedy H, GiacuUi F, Berg K, et al. Use of a reference material proposed by the International Federation of Clinical Chemistry and Laboratory Medicine to evaluate analytical methods for the determination of plasma lipoprotein (a). Clin Chem 2000 46 1956-67. 

Tate JR, Berg K, Couderc R, Dati F, Kostner GM, Marcovina SM, et al. International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Standardization Project for the Measurement of Lipoprotein(a). Phase 2 selection and properties of a proposed secondary reference material for lipopro-tein(a). Chn Chem Lab Med 1999 37 949-58... 

Tonometry may be achieved by simple homemade assem-bhes or by cormnerdaUy available equipment. Some commercially available tonometers use a thin-film technique. It consists of a glass or plastic cup fitted on a shaft and enclosed in a humidified chamber whose temperature is maintained at 37 C. A few milliliters of blood is placed in the cup, and gas flow is initiated to continuously flush the inside surface of the cup with the humidified gas. A controller unit causes the cup to rotate rapidly and periodically in short bursts, so that the blood in the cup is thrown in a thin layer over the inside walls. Another form of tonometry is the bubble technique. It uses a syringe that is specially constructed to allow gas to be introduced and humidified through the plunger. During tonometry, the syringe is laid in a thermostatically controlled aluminum heat block. Additional detail on tonometry and its applications can be found in a previous edition of this textbook. Reference conditions for tonometry have been recommended by a committee of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). ... 

University of Regensburg, Institute for Clinical Chemistry and Laboratory Medicine, Franz-Josef-Strauss-Allee 11, 93042 Regensburg, Germany e-mail gerd.schmitz klinik.uni-regensburg.de... 

---