First, there are many reasons for people to have enlarged red blood cells called macrocytosis, and a person may have macrocytosis and abuse alcohol, but not necessarily have macrocytosis from their alcohol use. Nevertheless, your sister's macrocytosis may be associated with her alcohol use
There are multiple causes of macrocytosis, but the two of the most common causes are deficiencies in vitamin B12 and folic acid. Alcohol abuse can certainly be associated with poor nutrition and therefore lead to deficiencies in B12 and folic acid, but there are several other important ways that alcohol is associated with macrocytosis.
Alcohol abuse can lead to macrocytosis through a variety of medical problems including liver disease, increased risk of bleeding
, direct toxic affects of alcohol on the bone marrow, and as already mentioned poor nutrition. A person who abuses alcohol can have macrocytosis from any one of these causes or from a combination of causes. However, there are also other important causes of macrocytosis not associated with alcohol use. Chief among them is pregnancy. Other causes include hypothyroidism, disorders of the bone marrow, increased production of immature blood cells, and certain medications. If the macrocytosis is associated with you sister's alcohol use the most important treatment is to seek help with her drinking. Your sister's primary care physician
can check a number of blood tests that will help him or her determine which potential causes are most likely and direct her to the best treatments.