Husband Has Polycythemia And Has For 15 Years Now And

Husband has polycythemia and has for 15 years now and has pint of blood drawn off once a month to keep a hemoglobin of 15; for last two months has been told his body has too much iron and been pulling it off; now last visit was told wanted to do a guided ct of bone marrow and do biopsy. suggestions of what it is?