Hemochromatosis Support Group
Hemochromatosis is a hereditary disease characterized by improper processing by the body of dietary iron which causes iron to accumulate in a number of body tissues, eventually causing organ dysfunction. It is the main iron overload disorder. Hemochromatosis is notorious for having symptoms that are often initially misattributed to other diseases.
Yes, 640 is still way too high for safety. If you go to a blood specialist doctor he/she will highly want it dropped to less than 100. I would not rely on a PCP to know what you should do.
For example, I will use my experience. My ferritin levels varied between about 600 to 1,000 (one test), with an average of 800 over several months. My PCP did not have a clue, and even my GI doctor was blaming it all on me having known fatty liver disease. The GI doctor did do a DNA test that showed that I have one of the two genes that can cause Hemochromatosis. (I had the same results from "23 and Me" a few years earlier.) To make things even more confusing, to me anyway, is that my wife has both genes that cause Hemochromatosis, but she has very low ferritin and our common blood doctor says that she does not have Hemochromatosis.
In my case, I do have Hemochromatosis that causes my high ferritin levels. The only way to get ferritin down to normal levels is to do blood donations using a prescription to allow your local blood center to take blood donations more than FDA mandated a minimum of 56 days between normal donations. Wierd, but the human body can store iron all the over the body, but cannot retrieve it, you must drain the swamp yourself. (The above donation process can vary by state; I live in Texas.)
Again in my case, last summer I did 8 donations in 9 weeks that resulted in my ferritin level to drop to 13, and my other iron panel numbers (which were all normal in the beginning) also were reduced to anemic levels. So my donations stopped, but with Hemochromatosis there really is no end because of Hemochromatosis (also called iron overload" BTW) will always keep storing iron continually. So, as of last week (one year later), my ferritin test came back as 150 (which can be considered normal by many labs), but for me, that met that I am going back to the blood center to do three donations, 8 weeks apart. That should bring my ferritin level back down to low normal. I will have to continue this type of process for the rest of my life.
IMO, you need to see a blood specialist ASAP. High ferritin levels can cause a long list of symptoms that can lead your doctor(s) down a long, and useless, road trying to find a cause of your specific problems.
Good luck and high ferritin can be easily cured by draining the swamp. Finding the root cause may be more difficult.