First, some good news: I am now 6 weeks past my iron infusion (1000 mg ferrous carboxymaltose, or InjectaFer, which raised my ferritin from 18 to 289). I am now getting significant reduction in my RLS symptoms. I now get complete control of my symptoms and sleep soundly through the night with about 30% less medication. I dropped my rotigotine patch from 3 to 2 mg, and my gabapentin from 2100 to 1500 mg. (I still take 5 mg methadone each evening, but may soon try dropping that as well.)
Now I want to address and hopefully clear up some confusion regarding how many of us are likely to benefit from IV iron therapy. I've seen numbers anywhere from 18% to 80%, with no evidence provided. So I went looking for some published evidence. I'm taking the following numbers from the excellent recent publication on iron therapy, written by several highly-regarded RLS experts:
The authors cite three class 1 studies (meaning well-designed, double-blind), all of which reported significant positive responses to IV infusions of ferrous carboxymaltose. (See section 5.3.1] Because these were all designed somewhat differently, with different end time points, the numbers vary somewhat. But here are the ranges reported among the three studies:
Complete remission (requiring no further RLS medication), IRLS score <=10: 30%, 38% at 4 and 6 weeks, and 25%, 38% at 20 and 30 weeks. (3rd study did not report on complete remission).
Partial responders (decrease in IRLS score by at least 40% - 50%): 37%, 45%, 60% from the 3 studies.
So as you can see, it's hard to cite just one number. But the results are definitely encouraging, and are backed up by good evidence. They did not find equally strong evidence for other iron infusion formulations, but they do report on them. So they reserve their highest recommendation for ferrous carboxymaltose (InjectaFer). (Note: the evidence for efficacy of oral iron therapy is less solid: there are no Class 1 studies supporting it. But the authors note that clinical experience supports its "probable efficacy".)
I hope these numbers, as well as my own positive results, might encourage some of you to have your ferritin levels checked and investigate the possibility of oral or IV iron therapy.