Point of care testing

The methods for measuring some biological compounds in blood and urine have become so robust and simple to use that measurements can be made away from the laboratory – by the patient’s bedside, in the ward sideroom, at the GP’s surgery, at the Pharmacy or even in the home. Convenience and the desire to know results quickly, as well as expectation of commercial profit by the manufacturers of the tests, have been the major stimuli for these developments. Experience has shown that motivated individuals, e.g. diabetic patients, frequently perform the tests as well as highly qualified professionals.

The immediate availability of results at the point of care can enable the appropriate treatment to be instituted quickly and patients’ fears can be allayed. However, it is important to ensure that the limitations of any test and the significance of the results are appreciated by the tester to avoid inappropriate intervention or unnecessary anxiety.

Outside the laboratory

Table 4.1 shows what can be commonly measured in a blood sample outside the normal laboratory setting. The most common blood test outside the laboratory is the determination of glucose concentration, in a finger stab sample, at home or in the clinic. Diabetic patients who need to monitor their blood glucose on a regular basis can do so at home or at work using one of many commercially available pocket-sized instruments.

Table 4.1

Common tests on blood performed away from the laboratory

Analyte	Used when investigating
Blood gases	Acid–base status
Glucose	Diabetes mellitus
Urea	Renal disease
Creatinine	Renal disease
Bilirubin	Neonatal jaundice
Therapeutic drugs	Compliance or toxicity
Salicylate	Detection of poisoning
Paracetamol	Detection of poisoning
Cholesterol	Coronary heart disease risk
Alcohol	Fitness to drive/confusion, coma

Figure 4.1 shows a portable bench analyser. These analysers may be used to monitor various analytes in blood and urine and are often used in outpatient clinics.

Fig 4.1 A portable bench analyser.

Table 4.2 lists urine constituents that can be commonly measured away from the laboratory. Many are conveniently measured, semi-quantitatively, using test strips which are dipped briefly into a fresh urine sample. Any excess urine is removed, and the result assessed after a specified time by comparing a colour change with a code on the side of the test strip container. The information obtained from such tests is of variable value to the tester, whether patient or clinician.

Table 4.2

Tests on urine performed away from the laboratory

Only gold members can continue reading. Log In or Register to continue