stjohnh wrote:Bridgercan wrote:...A year ago, I had two ferric carboxymaltose IV treatments; sadly no change in symptoms noted in the weeks and months following. Another mystery...
Unfortunately, IV Iron helps only around 50% of those that get it. Not clear why, but RLS is definitely a heterogeneous disease affected by a bunch of different genes. Its possible that some people have BID on the basis of abnormal endogenous opioid production or receptors, or as others have pointed out, that the blood-brain barrier iron-transport functions are so abnormal in some people that the high blood iron from an IV infusion is still not high enough to get the needed amount of iron into the brain.
RLS onset in childhood and teenage years happens, but it's less common than onset in a later age (AFAIK). If it's a genetic issue with iron transport, why is RLS in children rare? And how does augmentation come into this?
Once more I would caution against putting all eggs in one basket (BID theory). Don't stop exploring the other theories. If iron IVs help only 50% of patients, there are at least two possible conclusions: (a) the iron doesn't reach the brain or (b) iron is not the problem for these patients. Do we have any hard evidence that (a) is more likely than (b), or even that it's always (a)? Some patients have no problems at all with low iron levels. It is wide open if high iron levels are good or bad (and how high or low iron translates to the parameters that we can measure today, as we don't have a reliable indicator yet). Some doctors claim that iron levels should be as low as possible as long as you don't have anemia. (I disagree with them, but I can't prove them wrong as we lack the hard data.)
There is one practice that I strongly recommend: The more I start to believe in some theory, the more time I spend thinking about alternatives and criticism. We do go blind on one eye if we are set on a theory, and tend to adapt facts to the theory and not the other way around. I don't think all the facts fit the BID theory, and we can't afford to ignore them, even if the BID theory may be correct for 90% of the patients. If it's wrong even for 10% then we're not yet close to understanding the RLS pathogenesis.
Something may appear obvious, but it can still be incorrect. 40 years ago everybody "knew" that eating saturated fat leads to high saturated fat in the blood (triglyzerides), high cholesterol and CVD. So we replaced saturated fat with carbohydrates and vegetable oils, sugar with artifical sweeteners, and boom! diabetes increased by a factor of 4, obesity by a factor of 3.(We have very well designed studies today that fat in the blood is mainly driven by carbs in the diet, so high-fat low-carb diet lowers triglyzerides. Which is totally counterintuitive, but perfectly logical if you go into the bichemical details.)