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macrocytic anemia
Etiology:
1) pure red cell aplasia
2) liver disease, alcoholism
3) aplastic anemia
4) megaloblastic anemia
a) vitamin B12 deficiency
- Crohn's disease
b) folate deficiency
c) copper deficiency
d) myelodysplastic syndrome
5) hemolytic anemia
6) sideroblastic anemia*
6) cold agglutinin disease
7) hypothyroidism
8) pharmaceutical agents
a) interference with folate metabolism
1] alcohol
2] zidovudine (AZT)
3] phenytoin
4] primidone
5] phenobarbital
6] oral contraceptives
7] triamterene
8] sulfasalazine
9] sulfamethoxazole
10] methotrexate
b) inhibition of purine or pyrimidine synthesis
1] azathioprine
2] 5-fluorouracil
c) inhibition of deoxyribonucleotide synthesis
1] hydroxyurea
2] cytarabine
3] metformin (vitamin B12 deficiency) [6]
4] proton pump inhibitors (vitamin B12 deficiency) [6]
* MKSAP17 classifies sideroblastic anemia as macrocytic anemia; a dimorphic population of erythrocytes is observed, some are macrocytic, others hypochromic & microcytic
Laboratory:
- complete blood count (CBC)
- increased MCV > 100 fL
- perpheral smear
- target cells with MCV of 105-110 fL & acanthocytes (spur cells with spicules) suggest liver disease & hyposplenism
- see megaloblastic anemia
- anemia associated with MCV > 115 fL rules in megaloblastic anemia [3]
Interactions
disease interactions
Related
5-fluorouracil [5-FU] (Fluoroplex, Efudex, Adrucel, Carac)
aplastic anemia
azathioprine (Azanin, Imuran, Imurel)
cold agglutinin
cytosine arabinoside; cytarabine (Cytosar, ARA-C, HiDAC, Depocyt)
deoxyribonucleotide
hemolytic anemia
hydroxyurea; hydroxycarbamide (Hydrea, Droxia)
hypothyroidism
methotrexate (Rheumatrex, MTX)
oral contraceptive (OC)
phenobarbital; PB; PHB (Luminal, Barbita, Solfoton)
phenytoin; diphenylhydantoin; PTN (Dilantin, Dephenylan, Antilepsin)
primidone; desoxyphenobarbital (Primaclone, Mysoline)
purine
pyrimidine
sulfamethoxazole [SMX] (Gantanol, Aposulfatrim, Bactoreduct)
sulfasalazine (SSZ, Azulfidine, SAS)
triamterene (Dyrenium)
zidovudine; azidothymidine; AZT (Retrovir)
Specific
megaloblastic anemia
sideroblastic anemia
General
anemia
References
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed)
Lippincott-Raven, Philadelphia, 1998, pg 411
- Schiller G, in: UCLA Intensive Course in Geriatric Medicine &
Board Review, Marina Del Ray, CA, Sept 12-15, 2001
- Medical Knowledge Self Assessment Program (MKSAP) 14, 16, 17, 18.
American College of Physicians, Philadelphia 2006, 2012, 2015, 2018.
- Medical Knowledge Self Assessment Program (MKSAP) 19
Board Basics. An Enhancement to MKSAP19.
American College of Physicians, Philadelphia 2022
- Galloway M, Hamilton M.
Macrocytosis: pitfalls in testing and summary of guidance.
BMJ. 2007 Oct 27;335(7625):884-6.
PMID: 17962289
- Green R, Dwyre DM.
Evaluation of Macrocytic Anemias.
Semin Hematol. 2015 Oct;52(4):279-86. Review.
PMID: 26404440
- NEJM Knowledge+ Hematology