A new report suggests that health tests for the "worried well" can do more harm than good and casts doubts on their benefits.
The study said that most tests are not designed to be used by people who are not ill, are not researched or adequately regulated and can cause harm.
The report examined a host of different tests, including those bought over the internet to check liver function, home kits for prostate cancer and full body "MOTs" which are offered by private clinics.
It has been published by the group Sense about Science, and is backed by the Association of Clinical Biochemistry, the PHG Foundation charity and the Royal College of Pathologists.
It said: "Laboratory diagnostic tests look for the presence of a biomarker, such as a particular genetic sequence in an individual's DNA; or the amount of a biomarker, such as the level of cholesterol in blood.
"Off-the-shelf testing kits do the same thing. Tests that measure biomarkers can only tell you the levels present.
"They do not tell you the implications this may have for your health. Just because something is present doesn't necessarily mean it is causing you harm."