ⓘ Urine test strip
A urine test strip or dipstick is a basic diagnostic tool used to determine pathological changes in a patients urine in standard urinalysis.
A standard urine test strip may comprise up to 10 different chemical pads or reagents which react to change color when immersed in, and then removed from urine sample. The test can often be read in as little as 60 to 120 seconds after dipping, although certain tests require longer. Regular testing of the urine with multiparameter strips is the first step in diagnosing a variety of diseases. The analysis includes testing for the presence of proteins, glucose, ketones, hemoglobin, bilirubin, urobilinogen, acetone, nitrite and leucocytes as well as testing of pH and specific gravity or to test for the presence of various pathogens.
The test strips consist of a ribbon made of plastic or paper of about 5 mm wide, plastic strips have pads impregnated with chemicals that react with compounds present in urine producing a characteristic colour. On the paper strip the reactants are absorbed directly onto the paper. Paper strips are often specific to one reaction, for example, measurement of pH, while the strips with pads allow several definitions at the same time.
There are strips which serve different purposes, such as qualitative strips that only determine if the sample is positive or negative, or there are semi-quantitative ones that in addition to positive or negative reactions are also evaluating the quantitative output, in the latter the colour reactions are approximately proportional to the concentration of the substance when testing for sample. Reading of the results is performed by comparing the color panel with the color scale provided by the manufacturer, no additional equipment is required.
This type of analysis is very common in the control and monitoring of patients with diabetes. The time required for the appearance of the test strip can vary from a few minutes after the start of the test to 30 minutes after immersion of the strip in the urine depending on the brand of product used.
Semiquantitative values are usually stated as: trace, 1, 2, 3 and 4, although the tests can also be measured as milligrams per deciliter. Automated readers of the test strips also give the results using units of international system of units.