The results of health tests are interpreted by comparing the measured value or the signal given by the test with the reference values or result options described in the user manual. The correct interpretation requires that the test has been carried out in accordance with the instructions and that the result is proportional to one’s own situation. Below, we will go through the key questions that will help you understand the significance of the health test result.
What do reference ranges and test cutoffs mean?
A laboratory reference range describes results typical of a defined reference population. It differs from a rapid test’s cutoff, which determines how that test classifies a result. Ranges and cutoffs depend on the analyte, sample and method; use the values and instructions supplied with the specific result.
A result within a laboratory reference range is not a guarantee of health, and a result outside it does not automatically establish disease. A rapid test instead reports a result such as positive, negative or invalid according to its specific cutoff and instructions. For example, a hormone screen alone cannot diagnose menopause.
It is important to remember that the reference value is a statistical concept. A small percentage of healthy people can get a result outside the reference values without it being an actual health problem. Therefore, a single test result gives an indication of the situation, but does not solve it on its own.
What is the difference between a positive and negative test result?
The significance of a positive and negative result depends on the principle of operation of the test and the instructions for use. In some tests based on a competing immunoassay, the absence of a test line may indicate a preliminary positive result, while in other tests, the appearance of a line means a positive result. The interpretation is always made according to the instructions for the product in question and the approved reading time. Neither result alone is a diagnosis.
In a pregnancy test, a positive result means that the hormone hCG has been detected in the urine. In a drug test, a positive result indicates that the substance in question or its breakdown product has exceeded the threshold value of the test. A negative result, on the other hand, means that the substance was not detected with the sensitivity of the method used.
It is always advisable to read the result in parallel with the instructions for use, as the appearance of a positive and negative mark varies from test to test. In some tests, even a single weak line counts as a positive result.
Can a home test result be incorrect?
Yes. The result of a rapid test can be affected by, among other things, sampling, test storage, reading time, test restrictions and possible disturbing substances. A rapid test should not be described as equivalent to a laboratory test. An incorrect result can be either a false positive or a false negative, and it is usually due to a human or technical error in performing the test.
The most common reasons for an incorrect result are:
- testing too early for the target to reach a detectable level
- incorrect sample collection or storage
- not following the test instructions
- an expired test or exposure to unsuitable temperature or humidity
- interference from a medicine or another substance
If a result is unclear or unexpected, follow the instructions for repeating the test and seek healthcare advice where appropriate. Repeating a rapid test is not the same as laboratory confirmation. Use the specific product’s intended use and limitations when choosing a health test.
When does a health test result require a doctor’s assessment?
A doctor’s assessment is always necessary when the result is positive and related to a health condition that may require treatment or further examinations. Even if the result is negative but the symptoms persist, or when the result is unclear, you should see a professional.
Practical examples of situations where a doctor’s assessment is recommended:
- a positive infection or sexually transmitted infection screening result
- hormone-related symptoms that affect quality of life
- a positive pregnancy test when confirmation or advice is needed
- a result that does not fit persistent symptoms
- repeated tests that give different results
A home test can inform your next steps, but it does not replace assessment by a healthcare professional. Seek advice when results are unclear or symptoms persist.
How are the results read differently in different test types?
Different test types display the results in different ways, and the way you read them depends on how the test works. Rapid tests usually show the result visually as lines, symbols, or color changes, while digital tests or tests sent to the lab can provide numerical values.
Reading the Results of a Rapid Test
With rapid tests, such as pregnancy tests or drug tests, the result is read visually after a specified amount of time has elapsed since the sample was added. The instructions for use specify exactly how many minutes after adding the sample the result is ready to be read and how to interpret the different marks. The number and meaning of the lines vary from test to test. Always check the user manual for the specific product to identify the control line, test line, and indicators of an invalid result.
Interpreting Numerical Values
In hormone tests and genetic test reports, results may be presented as numerical values or verbal summaries. The interpretation of tests sent to a laboratory that provide numerical results depends on the method used, the reference range, and the report’s instructions.
Common to all test types is that reading the user manual before performing the test is essential for the correct interpretation. In an unclear situation, the customer service of the manufacturer or online store can help you understand the results.
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