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Macrocytosis is a condition where red blood cells are larger than normal.[1] These enlarged cells, also known as macrocytes, are defined by a mean corpuscular volume (MCV) that exceeds the upper reference range established by the laboratory and hematology analyzer (usually >110 fL).[2] Upon examination of a peripheral blood smear under microscope, these macrocytes appear larger than standard erythrocytes. It’s noteworthy that macrocytosis is a common morphological feature in neonatal peripheral blood.[3] The presence of macrocytosis can indicate a range of conditions, from benign, treatable illnesses to more serious underlying disorders.
Macrocytosis
 | |
|---|---|
| Other names | Macrocytes |
| Specialty | Hematology |
| Symptoms | Shortness of breath, weakness, heart murmur, tachycardia |
| Causes | Vitamin B12 deficiency, Folic acid deficiency, Malabsorption, Alcoholism |
| Risk factors | Bone marrow failure, hematologic malignancy |
| Diagnostic method | Symptoms, Complete blood count, Peripheral blood smear, Vitamin B12 level, Red cell folate level |
Types
editMacrocytes may be oval or round. Oval macrocytes (also called megalocytes)[4] are seen in conditions associated with dyserythropoiesis including megalobalstic anemia, myelodysplstic syndromes, Fanconi anemia and CDA type I & III. Round macrocytes are associated with other causes of macrocytosis.
Causes
editIn humans, the most prevalent causes of macrocytosis are often linked to alcoholism and deficiencies in vitamin B12 or folic acid (Vitamin B9), or a combination of these factors.[5] These conditions can affect the production and development of red blood cells, leading to their enlargement. Another cause of macrocytosis is benign familial macrocytosis, which is a hereditary condition that doesn’t present any symptoms.[6] Despite the larger size of the red blood cells, individuals with this condition typically have normal red blood cell function. It’s always important to consult with a healthcare professional for accurate diagnosis and treatment. Causes of Macrocytosis may include:
- Megaloblastic Anemia due to vitamin B12/ Folate deficienciy or their abnormal metabolism
- Poor dietary intake including strict veganism
- Increased requirements
- Pernicious anemia
- Malabsorption syndromes
- Alcoholism
- Smoking
- Reticulocytosis due to hemolysis, hemorrhage & Hemetenics
- Hypothyroidism
- Myelodysplastic syndromes (MDS)
- Congenital dyserythropoietic anemia
- Aplastic anemia and bone marrow failure syndromes
- Inherited disorders of DNA synthesis
- Homocystinuria
- Lesch-Nyhan syndrome
- Deficient enzymes for folate metabolism
- Liver disease
- Chronic obstructive pulmonary disorder (COPD)
- Drugs including folate antagonists, purine antagonists, tyrosine kinase inhibitors, anti-HIV drugs etc.
Complications
editNo complications arise from macrocytosis itself and a prognosis will be determined from its cause.
See also
editReferences
edit- ^ Kaferle, Joyce; Strzoda, Cheryl E. (2009-02-01). "Evaluation of macrocytosis". American Family Physician. 79 (3): 203–208. ISSN 0002-838X. PMID 19202968.
- ^ Woodruff, James N.; Blanchard, Anita K. (2016-06-11). Primary Care of Adult Women, An Issue of Obstetrics and Gynecology Clinics of North America. Elsevier Health Sciences. ISBN 978-0-323-44623-5.
- ^ Bain, Barbara J. (2015-01-20). Blood Cells: A Practical Guide. John Wiley & Sons. ISBN 978-1-118-81733-9.
- ^ Anderson, Shauna Christine; Poulsen, Keila (2003). Atlas of Hematology. Lippincott Williams & Wilkins. ISBN 978-0-7817-2662-7.
- ^ Pacholok, Sally; Stuart, Jeffrey J. (2011-01-01). Could It Be B12?: An Epidemic of Misdiagnoses. Linden Publishing. ISBN 978-1-61035-065-5.
- ^ "Macrocytosis: Practice Essentials, Pathophysiology, Etiology". 2022-10-07.
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