Over a third of patients admitted to intensive care develop hypernatremia (raised serum sodium concentration) or hyponatremia (reduced plasma sodium concentration) within a few days of admission. Both hypo- and hypernatremia acquired after admission prolong hospital stay and decrease chance of survival.  These are the ...

The anticoagulant potassium ethylenediaminetetra-acetic acid (K+ EDTA) is present in sample tubes used to collect samples for full blood count (FBC) and some other tests. However, the anticoagulant has the effect of markedly increasing plasma potassium concentration and reducing plasma calcium, magnesium and zinc...

Blood gas analysis has been performed at the point of care for well over 20 years and is sufficiently established for clinicians to have no misgivings about using pH, pCO₂ and pO₂ results obtained at the point of care for direct patient management.  Modern blood gas analyzers now have the capacity to measure not only...

Reduced plasma sodium concentration (hyponatremia), the most common electrolyte abnormality in hospitalized patients, is the subject of a recently published review. Disordered secretion of the pituitary hormone vasopressin (alternative name, antidiuretic hormone ADH) is central to the pathogenesis of hyponatremia for...

Hospitalized patients are frequently prescribed parenteral fluids and in most instances these are hypotonic (e.g. 0.18 % NaCl in 5 % dextrose). Controversy surrounds the routine use of hypotonic parenteral fluids because they can cause hyponatremia (reduced plasma sodium concentration), which if sufficiently severe...

Homeostatic mechanisms ensure that in health the extracellular fluid (ECF) concentration of electrolytes, including calcium, is maintained within well-defined limits. Abnormality in ECF calcium concentration can have profound adverse effects.  The most common means of assessing calcium status is to measure total...

Plasma sodium and chloride concentration are routinely measured using either a direct or indirect ion-specific electrode (ISE). Direct ISE is the technique employed in blood gas and most other point-of-care analyzers whereas indirect ISE is used in the majority of biochemistry profiling analyzers sited in central...

Clinical laboratories should have a policy mandating staff involved in analysis of patient samples to convey critical results to clinical staff urgently, usually by telephone. A critical result has been defined as a result "at such variance with normal as to be life threatening, unless something is done promptly, and...

Measurement of plasma/serum sodium concentration is one of the most frequently requested blood tests in clinical practice. Although usually performed in the laboratory, the test is also available at the point of care using technology incorporated into blood gas and other point-of-care analyzers. In health, sodium...

Measurement of blood lactate provides clinicians with a valuable means of identifying and monitoring critically ill patients who are suffering clinical shock as a result of severe trauma, sepsis or cardiogenic shock. Lactic acid accumulates in the blood of these patients due to the tissue hypoxia that results from...