Some drugs require a baseline bloodtest study to compare to future results to help detect known side effects of that drug. For example cholesterol lowering drugs can effect the liver and muscle. So they do a base line study of liver and muscle enzymes and repeat them every so often to monitor.
Although not quite the same analogy,The FDA and Merck should require a baseline study of all Propecia users. Wouldn't that be of some value to all of us right now In the long run maybe that will be a result of this forum.