My 89 Year Old Father, Just Got Home From The

My 89 year old father, just got home from the Doctor, They told him he is 4 Pints low in Blood, His white Blood Cells are low, Red Blood Cells are low and he is low on iron. Also has low Blood Pressure. They said that they can not do anything until he looses another pint. He is very weak. I am afraid that he is going to fall and maybe pull my mother down with him. What is causing this and is there anything he can do at home to build his Blood?