What are the health risks of low hemoglobin levels?

Find the cause: Very low hemoglobin levels will restrict your exercise tolerance, but the greatest danger of anemia is that it warns of an underlying problem. While the cause is often a woman's loss each month or during pregnancy, or non-supplementing vegetarianism, anemia may warn of cancer, ulcers, B12 deficiency which can cause brain damage, and a host of other bad things.

Etiology?: The etiology needs to be addressed first. Is it underproduction? ( bone marrow) Nutritional deficiency? Early cell death? Reduced erythropoietin levels(kidney disease) Blood losses like in excessive menses etc. Depends on primary cause