Excess prolactin combined with excess estrogen is a recipe for gyno. Deca can cause excess prolactin, while the test will cause the excess estrogen. It is my understanding (not 100% sure how accurate this is, however, so take it with a grain of salt) that prolactin will actually cause the nipple to secrete stuff (aka: if he squeezed his nipple [kinda like tryin to milk it (yes, I know that sounds gay)] and a drop [or a few drops] of a clear substance is secreted, then there is probably a prolactin issue [along with an estrogen issue too]). If no liquid, then it's prob just estrogen... either way, go with the letro..