Macrocytic anemia
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| Macrocytic anemia | |
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| Megaloblastic anemia blood smear | |
| ICD-10 | D51.1, D52.0, D53.1 |
| ICD-9 | 281 |
| DiseasesDB | 29507 |
| MeSH | D000749 |
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Macrocytic anemia Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Macrocytic anemia On the Web |
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American Roentgen Ray Society Images of Macrocytic anemia |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]
Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Macrocytic anemia from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms
Physical Examination
Laboratory Findings
Electrocardiogram
Chest X Ray
CT
MRI
Echocardiography or Ultrasound
Other Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Surgery
Primary Prevention
Secondary Prevention
Cost-Effectiveness of Therapy
Future or Investigational Therapies
Case Studies
Case #1
Hematological findings
MCV is often >110. Hct can often be as low as 15. Elevated LDH and bilirubin are seen since dyserythopoesis leads to destruction of >90% of RBC precursors. Hypersegmentation of PMNs is quite sensitive (>5% with 5 or more lobes or >1% with 6 lobes). Reticulocyte, WBC and platelets are low to normal. In one series of patients with B12 deficiency, 64% had a MCV greater than 100, and only 29% had anemia. In general the blood film can point towards vitamin deficiency:
- Decreased red blood cell (RBC) count and hemoglobin levels
- Increased mean corpuscular volume (MCV >95 fl often >110) and mean corpuscular hemoglobin (MCH)
- The reticulocyte count is normal
- The platelet count may be reduced.
- Neutrophil granulocytes may show multisegmented nuclei ("senile neutrophil"). This is thought to be due to decreased production and a compensatory prolonged lifespan for circulating neutrophils.
- Anisocytosis (increased variation in RBC size) and poikilocytosis (abnormally shaped RBCs).
- Macrocytes (larger than normal RBCs) are present.
- Ovalocytes (oval shaped RBCs) are present.
- Bone marrow (not normally checked in a patient suspected of megaloblastic anemia) shows megaloblastic hyperplasia.
- Howell-Jolly bodies (chromosomal remnant) also present.
Blood chemistries will also show:
- Increased homocysteine and methylmalonic acid in B12 deficiency
- Increased homocysteine in folate defiency
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Peripheral blood in megaloblastic anemia
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Howell-Jolly bodies
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Howell-Jolly bodies and erythroblast
Analysis
The Schilling test was performed in the past to determine the nature of the vitamin B12 deficiency, but due to the lack of available radioactive B12, it is now largely a historical artifact. Vitamin BTemplate:Ssub is a necessary prosthetic group to the enzyme methylmalonyl-coenzyme A mutase. BTemplate:Ssub deficiency leads to dysfunction of this enzyme and a buildup of its substrate, methylmalonic acid, the elevated level of which can be detected in the urine and blood. Since the level of methylmalonic acid is not elevated in folic acid deficiency, this test provides a one tool in differentiating the two. However, since the test for elevated methylmalonic acid is not specific enough, the gold standard for the diagnosis of B12 deficiency is a low blood level of B12. Unlike the Shilling test, which often included B12 with intrinsic factor, a low level of blood B12 gives no indication as to the etiology of the low B12, which may result from a number of mechanisms.
Treatment
- Folate is administered 1mg QD. Higher doses may be required in malabsorptive syndromes. It is empirically given to those with SCD and those on HD.
- B12 must be given as a load then maintenance. Most advocate 1000 mcg IM Qweek x4 then 100mcg/month.
- LDH falls in 2 days. Hypokalemia requiring replacement can occur in the acute phase as new cells are being generated rapidly.
- A reticulocytosis begins in 3-5 days and peaks in 10 days. The HCT will rise within 10days. If it does not, suspect another disorder. Hypersegmented PMNs disappear in 10-14 days.
- Neurologic abnormalities may take up to 6 months to resolve if ever. The longer the disease has been present, the worse is the prognosis for recovery.
- Persons with PA have a 2x risk of gastric CA (in some studies). Screen for occult blood.
el:Μακροκυτταρική αναιμία sq:Anemi makrocitike
References
gl:Anemia megaloblástica he:אנמיה מגלובלסטית it:Anemia megaloblastica sl:Megaloblastna anemija sr:Мегалобластна анемија