Medical test strips, especially those for at-home health monitoring, raise a common question: do they remain accurate past their expiration dates? Understanding the factors influencing test strip reliability, including shelf life and proper handling, is key to ensuring consistent and dependable results for personal health management.
Why Test Strips Expire
Test strips are diagnostic tools that rely on precise chemical reactions to measure substances in bodily fluids. Blood glucose test strips, for example, use enzymes like glucose oxidase or glucose dehydrogenase. These enzymes react with glucose in a blood sample, producing an electrical current that the meter interprets as a reading.
Over time, these sensitive chemical components degrade. Environmental factors like air, moisture, and extreme temperatures accelerate this breakdown. When reagents lose effectiveness, the strip’s ability to accurately react with the target substance is compromised. This leads to unreliable readings, making strips unsuitable for use past their expiration date. Manufacturers establish expiration dates to guarantee product performance under specified storage conditions.
Risks of Using Expired Strips
Using expired test strips leads to inaccurate readings, with serious implications for health management. These inaccuracies can be false high or false low results, both posing distinct dangers. For instance, with blood glucose monitoring, a false low reading might lead to insufficient insulin or delayed intervention, potentially causing dangerously high blood sugar (hyperglycemia) or even a diabetic coma.
Conversely, a false high reading could prompt too much medication or unnecessary dietary adjustments, risking dangerously low blood sugar (hypoglycemia). Such incorrect information can result in inappropriate medical decisions, delayed treatment, or unnecessary procedures. The FDA warns against using expired diabetes test strips due to the potential for inaccurate results and associated health risks.
Ensuring Accurate Test Results
To obtain accurate readings from test strips, proper handling and storage are necessary. Always check the expiration date on the container and do not use strips past this date. Many test strips also have a limited “in-use” shelf life once opened, often three to six months; note the opening date on the container.
Proper storage conditions maintain strip integrity. Store test strips in their original, tightly closed container in a cool, dry place, away from direct sunlight, heat, and excessive humidity. Ideal storage temperatures range from 36°F to 86°F (2°C to 30°C). When handling strips, ensure hands are clean and dry, avoiding contact with the test area to prevent contamination.
Some meters require “coding” or calibration to match test strip batches. While many newer meters feature auto-coding, if your device requires manual coding, ensure the code on the meter matches the code on the strip vial. Regularly using quality control solutions, as recommended by the manufacturer, verifies that both the meter and strips function correctly. Proper disposal of used or expired strips and lancets is also advised.