Electrolytes clinical diagnostics

Redox-inactive cations attract a particular interest for analytical chemists because of their importance in environmental control, industry, and medicine. For instance, in clinical diagnostics, tests for blood electrolytes (Na+, K+) are routine, because deviation of cation content from their normal values indicates a number of pathologies. 

Laboratory support is carried out by the clinical diagnostic laboratory and laboratory of tissue typing. The equipment of clinical diagnostic laboratory allows carrying out hematological, biochemical investigations for the structural subdivisions of the Center, coagulometry, analysis of the acid-alkali state, the electrolytes of blood and several other researches in the round-the-clock mode. 

Chemical sensors have been developed by companies such as DuPont and Cygus Therapeutic Systems for the measurement of blood electrolytes and gases, and ion selective membranes are common in many clinical analyzer systems. While the use of chemical sensors for such determinations will continue to increase, sensor applications in clinical diagnostics will favor development and application of biosensors due to the high specificity residing in the biological component of these sensors. 

In contrast to other analytical methods, ion-selective electrodes respond to an ion activity, not concentration, which makes them especially attractive for clinical applications as health disorders are usually correlated to ion activity. While most ISEs are used in vitro, the possibility to perform measurements in vivo and continuously with implanted sensors could arm a physician with a valuable diagnostic tool. In-vivo detection is still a challenge, as sensors must meet two strict requirements first, minimally perturb the in-vivo environment, which could be problematic due to injuries and inflammation often created by an implanted sensor and also due to leaching of sensing materials second, the sensor must not be susceptible to this environment, and effects of protein adsorption, cell adhesion, and extraction of lipophilic species on a sensor response must be diminished [13], Nevertheless, direct electrolyte measurements in situ in rabbit muscles and in a porcine beating heart were successfully performed with microfabricated sensor arrays [18],... 

The analysis of sweat for increased electrolyte concentration is used to confirm the diagnosis of cystic fibrosis (CF). CF is recognized as a syndrome with a wide spectrum of clinical presentations associated with a defect in the cystic fibrosis transmembrane conductance regulator protein (CFTR), a protein that normally regulates electrolyte transport across epithelial membranes. (For a more detailed discussion of CF, see Chapter 40.) Several hundred mutations of CFTR have been identified. Although mutational analysis is available, it is not informative in all cases, and the sweat test remains the standard for diagnostic testing. ... 

Hypokalemia (defined as a plasma potassium concentration <3.5 mEq/L) is one of the most commonly encountered electrolyte abnormalities in clinical practice. However, it is virtually nonexistent in otherwise healthy adults not receiving medication. This is partly explained by the high potassium content in the typical Western diet as well as the effective potassium-sparing mechanisms in the body to autoregulate the plasma potassium concentration. Hypokalemia usually occurs in patients who are receiving diuretic therapy. It has been estimated that as many as 50% of patients who receive diuretics have plasma potassium concentrations less than 3.5 mEq/L. ° Hypokalemia can be described as mild (serum potassium 3 to 3.5 mEq/L), moderate (serum potassium 2.5 to 3 mEq/L), or severe (<2.5 mEq/L). When hypokalemia is detected, a diagnostic work-up that evaluates the patient s comorbid disease states and concomitant medications should be initiated. 

Benjamin PP (1969) A rapid and efficient method of preparing c-human serum albiunin its clinical applications. Int J Appl Radiat Isot 20 187-194 Benjamin PP, Rejali A, Friedell H (1970) Electrolytic complexation of " Tc at constant ciurent its application in nuclear medicine. J Nucl Med 11 147-154 Clarke MJ, Podbielski L (1987) Medical diagnostic imaging with complexes of " Tc. Coord Chem Rev 78 253-331... 

The maintainance of water and electrolyte balance is one of the most important therapeutic activities in the clinic. Normal diet and adequate fluid intake cover one s requirements. Imbalance (see above) has to be verified by electrolyte determination in blood serum as well as in urine and possibly by other diagnostic parameters. Water equilibrium must be attained and compensation of electrolyte deficiency should be performed by oral or parenteral application of medicaments containing the required amount of electrolytes. A very large number of solutions and tablets is available to solve these clinical problems. For further details, see Refs. 27 and 41-44. 

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