MacroprolactinEMIA, as mentioned by Minnie, is different from macroprolactinOMA. There are actually two different kinds of prolactin molecules -- big ones and small ones. The small ones are the ones that cause the majroity of hyperprolactinemia, and are biologically active within the neuroendocrine cocktail. Prolactinomas come in two size categories -- micro and macro -- butr secrete one kind of prolactin -- the smaller and biologically-active molecule. There is another kind of prolactin called macroprolactin, but it is biologically inert and does not cause other symptoms of elevated prolactin. As far as I know, it is not secreted by a pituitary tumor at all -- in fact, I'm not sure where it comes from. It can mess up a prolactin test but does not affect the body the same way the "usual" prolactin does. Within the already-rare finding of hyperprolactinema, this "macro prolactin" molecule is rarer still. Macroprolactin -- also called "big-big prolactin" is a different kind of molecule that causes very high results on a prolactin blood test, but does not cause any physiologic symptoms. It's very rare, but it does happen. If you have very high prolactin levels that are not responding to the dopamine agonists, AND you have NO other symptoms of elevated prolactin or tumor (no headache, no vision changes, no sinus problems), this may be why. To clarify the other point -- very high prolactin levels can also be caused by larger tumors -- the macroprolactinOMAS -- but the prolacting that these tumors secrete is the small-molecule prolactin that IS biologically active, not the "big-big prolactin" which is not biologically active. HOw is that for confusing -- Minnie, perhaps you can help to clarify this if I've made it worse!! | 