I am old and have never donated blood since adolescence, but believe I should based on a close reading of my recent blood work. But I am also unvaxxed, and want to remain that way. Could you describe the blood donation process?
You answer questions, and they take your blood. The questions change from place to place.
Blood ferritin is the most useful iron stores test. The optimal amount is 70 ng/ml. Less than that is iron deficiency. Some people also test transferrin saturation.