Estrogen is a broad term covering a number of compounds which have similar effects. Estradiol is one particular compound, which is considered to be the ultimate hormone of the estrogenic pathway. There are a number of intermediate compounds which in ferrets can exert the same effects (hair loss, vulvar swelling, a return to intact behavior), but which are not yet estradiol.) For those who like to read the detailed information, at the BOTTOM of this post, I am including an abstract from Dr. Karen Rosenthal, who is the pioneer in hormonal testing of adrenal disease in ferrets. Let me summarize, though. Of the original 7 hormones tested in the original Tennessee profile, three hormones, (estradiol, 17-hydroxyprogesterone, and androstenedione) were considered significant. In this study, only 22% of ferrets had all three hormones elevated. Thus, if you are testing for only one of the three hormones (in this case estradiol), you run a significant risk of having the test being a false negative. Similar signs can result from elevations of 17-hydroxyprogesterone, or androstenedione (an androgen intermeidate of estradiol). The bottom line of Dr. Rosenthal's research was this: "Because concentration of a particular hormone was not high in all ferrets, we recommend determining plasma concentrations of several sex steroids, including androstenedione, 17-hydroxyprogesterone, and estradiol." Estradiol testing is available in a number of labs, not just Cornell's. If that particular test is elevated, you have your diagnosis. But if it is not, you haven't eliminated a diagnosis of adrenal disease. With kindest regards, Bruce H. Williams, DVM, DACVP Join the Ferret Health List at http://groups.yahoo.com/group/Ferret-Health-list [This post was followed by an abstract.] In reply to a further question about such hormonal tests: If you are not seeing evidence of adrenal disease in your ferrets (hair loss, vulvar swelling, a return to intact sexual behavior) then this is not a require part of the annual checkup. With kindest regards, Bruce H. Williams, DVM, DACVP Join the Ferret Health List at http://groups.yahoo.com/group/Ferret-Health-list [Posted in FML issue 3371]