Anemia, Megaloblastic

Prevalence: Estimates ranging from 1.7-3.6%.

Most common cause is vitamin deficiency: 65% vitamin B12; 12% combined folate/vitamin B12; 6% folate.

Pernicious anemia is less common: 1 in 7500 people in USA develops pernicious anemia each year.

Prevalence increases with advanced age and in countries with higher rates of malnutrition.

Risk of severe anemia and coagulopathy.

Risk of coronary, cerebral ischemia secondary to severe anemia.

Increased plasma volume as compensatory mechanism can predispose pts to CHF.

Exaggerated effect of myocardial depression from anesthesia.

Preoperative treatment should include supplementation of B12 and folate or transfusion in setting of severe anemia and emergent surgery.

Decreased platelet count and coagulopathy.

Anemia causing MI, stroke, or resp failure.

An anemia caused by a failure of DNA synthesis which results in large, structurally abnormal and immature red blood cells called megaloblasts (MCV >100 fL/cell).

Often WBC and platelet counts are also decreased.

Anemia develops insidiously and due to physiologic compensatory mechanisms it may not cause symptoms until it is severe.

Symptoms: Fatigue, pallor, dyspnea on exertion, headache, dizziness, tachycardia, nausea, diarrhea, glossitis, and jaundice.

Vitamin B12 deficiency can interfere with myelination and produce peripheral neuropathy which varies from subtle loss of vibratory sensation and proprioception to frank dementia.