Macrocytic Anemia Flashcards
What is macrocytic anemia?
Anemia with RBCs with a MCV > 100 Anemia is considered to be when: Hgb<12g/dL or Hct<36% in non pregnant Hgd<11g/dL in pregnant females Hgb<13g/dL or hct<41% in males
What is the pathophysiology in B12 or folate deficiency?
B12 and folic acid are essential for DNA replication and repair and are cofactors
Impaired DNA leads to abnormal cell division
What are sone causes of macrocytosis with or without anemia?
Drugs Alcoholism Alcoholic or non alcoholic liver disease Hypothyroidism B12 deficiency Folate deficiency Aplastic anemia Acute leukemia
What are the causes of B12 deficiency?
Elderly persons on a tea and toast diet
Strict vegan vegetarians
Lack of intrinsic factor: gastrectomy, pernicious anemia
Malabsorption of vitamin B12 secondary to drugs, tapeworm, sprue
What are the causes of folate deficiency?
Dietary deficiency Increased requirements of pregnancy Congenital deficiency Sprue Alcoholism Increased turnover: hemolysis or sickle cell Inherited disorders of DNA synthesis: Lesch Nyhan syndrome Drugs: methotrexate, phenytoin Liver disease
What is the physical findings of macrocytic anemia?
Atrophic glossitis
Hyperpigmentation of skin, creases and oral mucosa
What are the labs to consider for diagnosis?
CBC
Peripheral blood smear- hypersegmented neutrophil
B12 and folate levels decreased
Indirect bilirubin through CMP
What are the tests for B12 deficiency?
Schilling test- not done as much
Urine for methylmalonic acid
Anti parietal cell test
Anti intrinsic factor antibody test
What are the tests for folate deficiency?
Serum folate- changes based on diet
RBC folate- not affected by diet
Algorithm for macrocytic anemia work up
Presence of macrocytic anemia
Consider drugs, alcohol, B12; folate
B12, folate low—-> investigate/treat
B12: folate normal ->check liver function, thyroid
No significant anemia- consider alcohol
Anemia- consider hematology, referral for bone marrow testing
Algorithm for B12, folate deficiency?
Presence of macrocytic anemia
Consider peripheral blood smear
Blood smear abnormal - non megaloblastic or megaloblastic
Non megaloblastic- consider alcohol related
Non megaloblastic- reticulocyte count
Reticulocyte>2- suspect hemolysis
Reticulocyte <2- review B12 level
What are the B12 levels indicate?
B12<100- B12 deficiency B12>400- check RBC folate RBC folate low- folate deficiency RBC folate normal- bone marrow biopsy 100
What are the MMA and homocysteine levels indicative of?
MMA elevated and homocysteine elevated or normal- B12 deficiency
MMA normal and homocysteine elevated- Folate deficiency
MMA and homocysteine normal- bone marrow biopsy
How to treat macrocytic anemia?
Treat the underlying condition
B12 or folate replacement through diet, B12 IM shot monthly (1000mcg), folate 1mg PO daily
Tranfusion
