Sex hormone-binding globulin (SHBG) is thought to mainly function as a transporter and reservoir for the estradiol and testosterone sex hormones. However it has also been demonstrated that SHBG can bind to a cell surface receptor (SHBG-R). The SHBG-R has not been completely characterized. A subset of steroids are able to bind to the SHBG/SHBG-R complex resulting in an activation of adenylyl cyclase and synthesis of the cAMP second messenger.  Hence the SHBG/SHBG-R complex appears to act as a transmembrane steroid receptor that is capable of transmitting signals to the interior of cells.
My autoimmune disease is not life threatening, however, corticosteroids are the only available treatment for Polymyalgia Rheumatica. There is no alternative. I have had many relapses, NSAIDs do not work for this disease and anybody who thinks they can control PMR without steroids soon realises that the only way to beat the pain and live relatively normally is with steroids. Naturally, the dose is tapered gradually, but most people have it for 3 or 5 years or more, many like myself suffer relapes particularly if they get a viral infection, undergo surgery or have a major crisis in their lives, and some people never recover from PMR. It is a devastating disease and without steroids it is crippling. Of course there are side-effects but if one is careful about diet, exercise and plenty of rest they can be reduced. After 8 years on steroid treatment my bones are still strong. A thyroid nodule was found during an MRI to check on my spine, and I am referred to see a specialist, but an endocrinologist friend read the US report and says I have nothing to worry about. Thyroid nodules are common.