It is conflicting -- here is part of why. Prolactin is "pulsatile" - meaning that levels change throughout the day in response to all kinds of things. The list is very long, and includes basics like eating and sleeping to recent intimate activity, etc. . . to things you'd never imagine would affect prolactin levels, like caffeine and even the stress of the needle-stick for the blood draw. These are little changes rather than the big changes (or lack thereof) that doctors are looking for when they test us periodically. It's not always addressed in the medical articles, but when it is, it does say that the "best" way to understand someone's prolactin level is to draw blood when fasting, and to do it many times over a 24-hour period, in order to understand the big picture as well as the little changes during that time. Having said that, that kind of testing is very seldom done -- if ever -- because it is time consuming and expensive and not very much fun -- I don't recall seeing anyone here mention that they were tested this way. It also probably doesn't do much to change what our doctors recommend or the way they handle our treatment -- a "snapshot" from a single blood draw (along with what we tell them we are feeling and the results of other related tests as necessary ) is good enough for them to make treatment decisions -- and the serioes of snapshots from regular blood draws over time helps them to understand how things are going. The most important thing for those of us who test regularly (every few weeks or so) to see how we are doing on meds is to test under the SAME conditions as much as possible, whatever they are, rather than changing lots of things from one test to another. That way, fasting or not, they know what is "normal" for you and can determine how that is changing over time. So, if you decide to fast, then be sure you ALWAYS fast -- and have your blood drawn at the SAME lab at the SAME time of day each time you do it. I do mine every month: I do not fast; I go between 8-9 am; same lab every time. Its predictable -- I will have eaten roughly the same amount of food each time; will have had a couple cups of coffee; and will be halfway through a bottle of orange juice that I take with me and drink before/during/after as a hedge against getting dizzy during the blood draw. Rather than trying to second-guess all the little things that can alter levels, just know that they are always changing a little and that testing with "everything else consistent" will help give the best picture of how they are over time. Think of it the way pregnant women take pictures of their bellies over the 9 months of pregnancy: standing sideways in front of the same wall, wearing same shirt, so that what you see in the photos is the change in the size of their bellies (yes, pregnancy analogies continue in my postings) . . . I know I have seen articles on this posted elsewhere on the site. Minnie -- when you have a chance, can you help with linking in to the right one(s)? I'm not sure which they are -- or which ones are accessible easily to folks here. ![]() | 