Hard question to answer. It depends on you. Everybody at the right age should get one, and depending on the results, you may not need to do another one for several years.Because of course as you grow older, you're going to lose more bone. If you're terrific at 60, you might want to do another one at 65 to see what's happened.If you are low and you're going to be treated, we think it's a good idea to do it maybe a year or two later to verify that you're getting an effect.And most people on these medicines, if they take them, will get a benefit where the bone density will cease to go down, it will stay stable, it may be a smidgeon higher, and that's good.A response is stabilization or slight increase and you may want to do it every couple of years to verify that everything is still working.If it isn't stable, it may well not be that the drug didn't work, it may be that you've got something else going on, you're D deficient or something else is wrong, and that has to be determined.So the test, if it's good, tells you that things are going in the right direction. If the test is a little bit off, you need to be sorted out to see what, what's going on in you.