Medical Self-Tests Create Blind Spots for Clinicians

 Home tests have rapidly moved into the mainstream worldwide since the COVID-19 pandemic, offering discreet access to diagnostics without a clinic visit. The annual sales in Germany alone are estimated at €500 million, reflecting the speed of market growth. 

These self-test kits now cover a wide spectrum, including measurements of hormones such as testosterone, infection screening for gonorrhoea and chlamydia, colorectal cancer screening, thyroid function assessments, vitamin D measurements, and drug testing for substances.

For many patients, the appeal lies in privacy and speed of the process. Avoiding HIV or chlamydia diagnoses in official medical records, as well as long waits in clinics, has made home tests an attractive alternative that delivers rapid results at home.

Medical associations caution that this trend is creating a form of “parallel medicine,” where results are generated without medical history or clinical context. Self-tests only provide an indication, not a diagnosis, and without professional interpretation, the risk for false reassurance, misdiagnosis, or unnecessary consultations remains high.

Quality Concerns

One study reviewed the information provided for self-testing devices sold in the UK. The researchers evaluated over 30 self-tests that assessed 20 biomarkers for 19 different conditions. These results are concerning. 

Packaging and instructions were often incomplete or unclear. Only eight of the 30 tests provided information on who should or should not use the test. 

Only 23 included clear instructions on how the results should be interpreted. Information regarding the action to be taken after the test was absent from most of the test boxes.

Many devices did not explain whether high or low results required medical attention. Seven provided no guidance on the limit of detection or threshold used to define an abnormal test result.

Interpretation becomes particularly challenging when the results involve more than one laboratory value. 

Conditions such as vaginal infections or vitamin D deficiency require clinical context, including symptoms and risk factors, which necessitate medical expertise. Without this context, the results can be easily misinterpreted. 

This can lead to unnecessary consultations in some cases and missed serious conditions in others. Clinicians also face difficulties when patients present results without information on the test accuracy or thresholds applied.

Vitamin D testing shows how self-testing can conflict with medical guidance. 

The National Institute for Health and Care Excellence in the UK advises against the routine screening of asymptomatic individuals for certain conditions; however, such tests are widely marketed.

Prostate-specific antigen (PSA) self-testing raises the greatest concerns. It is often marketed as part of routine health checks or cancer screening tools. 

Such tests without medical advice are risky and cannot replace specialist screenings. 

The main concern is that patients may see normal results as reassurance or mistake abnormal results for a definite cancer diagnosis.

The European Union law sets strict requirements for self-testing. Under the In Vitro Diagnostic Regulation, tests must demonstrate sensitivity and specificity, ensure usability, and provide clear information so that users understand the significance of the results. Only after meeting these criteria can a product receive the European Conformity (CE) mark required for its legal distribution.

System Flaws

A scan of major online retailers shows a wide range of products, from cancer and infection tests to PSA, hormone, and vitamin D kits, often without a CE mark. Many of these products originate in China, are not legally authorized, and are barely regulated.

No reliable figures exist on the sales, use, or consequences of routine care. It is also unclear how many preventive screenings or necessary procedures are missed because patients rely on these questionable results.

Family physicians have long been responsible for preventive care and interpreting laboratory findings in a patient’s medical history. Millions of individuals are now generating and reading results on their own without professional guidance, putting the role of professionals to question.

The wider issue is whether self-testing reflects convenience or a loss of trust. 

The popularity of these products may signal flaws in healthcare systems, such as long wait times, barriers to access, lack of transparency, and poor communication. The decline in the acceptance of electronic medical records points to the same concerns.

https://www.medscape.com/viewarticle/medical-self-tests-create-blind-spots-clinicians-2025a1000ncz