His family have always donated on a regular basis so it took a long time to find out he has this condition. He literally had been inadvertently controlling the condition without known he had it by regularly donating blood.
But if he now doesn't have the blood removed on a regular basis, he'll die from toxic poisoning from iron build up in his body. Normally a body disposes of excess iron in the form of ferritin (a protein containing iron) via poo pourri hence why you have to consume it in a regular basis. People with haemochromatosis don't, so the body stores the excess in organs (in particular the liver and the brain) and joints which poisons the body, fatally if not dealt with. His first reading when he was just diagnosed was the highest any of the doctors (or blood banks) in this area have come across. I forget what the figures are for people without the condition (I looked it up, men 70-330 ng/mL), but I do know that when his current readings reach 100 (ng/mL) then he has to have blood removed again. His initial figure when first diagnosed was over 3,300 ng/mL. It took 18 months of removing 1 unit each week to get him to levels the medical profession were happy with. He looks and is much better now thankfully.
Removing blood regularly is the only way of forcing the body to pull the ferritin out of the organs/joints, and back into the blood so it can then be removed on the next cycle of blood letting. Once his levels are back within the accepted limits he's fine and just has a blood test regularly until it creeps back into danger area and the cycle starts again. But because his blood is high in this protein that stores iron, it is exceptionally useful to ICU patients who usually need it.