The number of medical tests available seem almost infinite. However, just because a test exists doesn't mean taking it is in your best interest, physically or financially. Using some tests as a screen won't really tell you what you need to know.
Dr. Roger Harms gives the example of ovarian cancer and some medical tests available for it. One such test is for CA125. It's associated with ovarian cancer, so it's worth doing, right? Dr. Harms disagrees.
"Yes, the test is associated with ovarian cancer, but that doesn't make it a good test. It's unchanged in most of the cancers you would want to find, the early ones, and it's present in many women who have other, non life-threatening conditions. The precision of the test, (its positive predictive value), is less than 3 percent. Using the test as a screen would harm women and cost a mint in downstream testing. Maybe in the future it will part of a screening strategy that works, but we're not there yet."
His suggestion? Say no to wasting resources and time, to indiscriminately going for every medical test available. Say no to the expense. Say no to tests that aren't going to help you.
http://www.mayoclinic.com/health/medical-tests/MY01288/rss=1