Thanks for the welcome! The link
@southernlady provided is great info. I'll add my experience too -
When my iron levels first got low, my GP was adamant that there was some form of oral iron that would work for me. I had to waste months proving him wrong (and get a blood transfusion in the process) before they finally determined that some other method was "medically necessary". I tried EVERYTHING - every form of iron known to man in massive, gut-busting, doses. First time out, my GP wanted to handle it "in-house" rather than sending me to a hematologist. So I got about 60 IM injections of Dextran in my butt/hips over the course of several months. It did restore my levels, though, and they held for several years (gradually declining, but not to a problematic level). In the meantime, I moved and had to get a different GP. He is the type that likes to refer out most anything that is complicated, so he sent me directly to a hematologist. I got a great one, and she set me up with an infusion of Feraheme. It is given in two doses, spaced one week apart. Basically, they just gave me an IV line and slowly pushed the meds in over a 10-minute period. Worked a treat. This last time that my levels got low, I had an infusion with Injectafer. It is newer and wasn't available last time I was low. Same deal, though, 2 doses one week apart. This one was a drip IV that was administered over 20 minutes.
Mine isn't annual, it is more like every 2 years. Basically, I just follow the labs religiously and let them know when I need it. To be honest, though, I don't really need the labs to tell me when the ferritin is low - I start CRAVING ice. CANNOT stop chewing it. It's horrible for my teeth and drives my daughter crazy, so I will get my labs early if that happens. I still find it amazing that within about 2 weeks of the infusions, I'm suddenly not at all interested in the ice.
Mine is all covered by my insurance, so I don't really know how much it costs. The nice thing is that I don't even have to take any oral iron in between infusions, since they truly have no effect. One less supplement is nice...