The population-based reference interval is the most widely used tool for interpretation of individual patient laboratory test results. The clinical value of those results depend crucially on the reference intervals with which they are compared, and all efforts directed at ensuring analytically precise and accurate...

All clinical procedures and treatments are associated with potential adverse effects of greater or lesser significance.  The undisputed value of blood testing for both diagnosis and monitoring of disease is tempered by the recognition that repeated blood sampling can result in blood loss of sufficient magnitude to...

Updated with new information from a 2008 article! Health demands that despite quite significant variation in its rate of production, the amount of carbon dioxide in blood is maintained within well-defined narrow limits. The homeostatic mechanisms that maintain the normal content of carbon dioxide in blood are...

The ‘gold standard’ sample for blood gas analysis is arterial blood obtained via an indwelling arterial catheter or by arterial puncture. For a number of reasons capillary blood is an attractive substitute sample that is routinely used in some clinical settings.  The purpose of this article is to examine the evidence ...

There are few medical diagnoses that depend solely on the result of a single blood test, but diabetes mellitus, which is defined by concentration of circulating glucose, is one that does. Quite apart from its long established role in diagnosis as well as life-long monitoring of diabetes, measurement of circulating...

The integrity and function of all cells depend on an adequate supply of oxygen. Severe acute illness is frequently associated with inadequate tissue perfusion and/or reduced amount of oxygen in blood (hypoxemia) leading to tissue hypoxia.  If not reversed, tissue hypoxia can rapidly progress to multiorgan failure and ...

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...

The significance of good practice during the pretesting phase of clinical laboratory investigation cannot be  overemphasized. The production of high-quality, accurate results which are clinically useful depends as much on practice before the patient’s sample reaches the laboratory as it does on the analytical phase...

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...

The principal function of the protein hemoglobin contained in red blood cells is transport of oxygen in inspired air from lungs to tissue cells. Although normally present in only trace amounts, there are three species of hemoglobin that cannot transport oxygen. The three species, collectively called the dyshemoglobins ...