redshoes wrote:Due to my total lack of medical background, I have only the vaguest idea why slow release iron products will increase the amount of iron that can be taken up by the body during the infusion process, or why slow-release is safer than the faster release formulations. ...
I think the idea is that due to the blood-brain barrier, coupled with faulty blood-brain barrier iron transport (genetic/RLS), that only if the ferritin is above a certain level (say 400 for example) will the iron seep across the blood brain barrier, but this only occurs slowly. If this is the mechanism, then fast release IV iron, which provides VERY high ferritin, but only for a short spell, will only have a day or few days in which the ferritin stays above 400 (in this hypothetical example). So the full dose of iron is in the blood stream and available to all organs in the body-- but only a small amount of it gets into the brain.
The slow release IV iron provides high ferritins, but only moderately high (say 500-1000), but for many weeks. So that instead of only a day or two when the ferritin is above 400, there are at least several weeks in which the ferritin is above that level, meaning much more will seep into the brain from the blood.
RLS is a heterogeneous disease, with multiple genes involved (further complicated by epigentic factors), so that person to person variability is very high. This means that some have mild symptoms, some severe. Some respond very well to IV iron (I am one of the lucky ones) but a significant minority don't have any improvement with IV iron at all. The reason for this is unknown currently.