Macrocytosis is a condition where

red blood cells Red blood cells (RBCs), referred to as erythrocytes (, with -''cyte'' translated as 'cell' in modern usage) in academia and medical publishing, also known as red cells, erythroid cells, and rarely haematids, are the most common type of blood cel ...

are larger than normal. 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 Hematology ( spelled haematology in British English) is the branch of medicine concerned with the study of the cause, prognosis, treatment, and prevention of diseases related to blood. It involves treating diseases that affect the production ...

(usually >110 fL). Upon examination of a peripheral blood smear under microscope, these macrocytes appear larger than standard

erythrocytes Red blood cells (RBCs), referred to as erythrocytes (, with -''cyte'' translated as 'cell' in modern usage) in academia and medical publishing, also known as red cells, erythroid cells, and rarely haematids, are the most common type of blood cel ...

. Macrocytosis is a common morphological feature in

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peripheral blood. The presence of macrocytosis can indicate a range of conditions, from benign, treatable illnesses to more serious underlying disorders.

Types

Macrocytes may be oval or round. Oval macrocytes (also called megalocytes) are seen in conditions associated with dyserythropoiesis including megaloblastic anemia, myelodysplstic syndromes, Fanconi anemia and CDA type I & III. Round macrocytes are associated with other causes of macrocytosis.

Causes

In humans, the most prevalent causes of macrocytosis are often linked to

alcoholism Alcoholism is the continued drinking of alcohol despite it causing problems. Some definitions require evidence of dependence and withdrawal. Problematic use of alcohol has been mentioned in the earliest historical records. The World He ...

and deficiencies in

vitamin B B vitamins are a class of water-soluble vitamins that play important roles in cell metabolism and synthesis of red blood cells. They are a chemically diverse class of compounds. Dietary supplements containing all eight are referred to as a vita ...

folate Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...

(vitamin B), or a combination of these factors. 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 does not present symptoms. Despite the larger size of the red blood cells, individuals with this condition typically have normal red blood cell function. Causes of macrocytosis may include: *

Megaloblastic anemia Megaloblastic anemia is a type of macrocytic anemia. An anemia is a red blood cell defect that can lead to an undersupply of oxygen. Megaloblastic anemia results from inhibition of DNA replication, DNA synthesis during red blood cell production. ...

due to deficiency or abnormal metabolism of vitamin B or folate ** Poor dietary intake, including due to strict

veganism Veganism is the practice of abstaining from the use of animal products and the consumption of animal source foods, and an associated philosophy that rejects the commodity status of animals. A person who practices veganism is known as a vega ...

** Increased requirements **

Pernicious anemia Pernicious anemia is a disease where not enough red blood cells are produced due to a deficiency of Vitamin B12, vitamin B12. Those affected often have a gradual onset. The most common initial symptoms are Fatigue, feeling tired and weak. Other ...

** Malabsorption syndromes * Alcoholism * Smoking * Reticulocytosis due to

hemolysis Hemolysis or haemolysis (), also known by #Nomenclature, several other names, is the rupturing (lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may ...

blood loss Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, v ...

and hematinics *

Hypothyroidism Hypothyroidism is an endocrine disease in which the thyroid gland does not produce enough thyroid hormones. It can cause a number of symptoms, such as cold intolerance, poor ability to tolerate cold, fatigue, extreme fatigue, muscle aches, co ...

* 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) * Certain drugs, including folate antagonists, purine antagonists, tyrosine kinase inhibitors, anti-HIV drugs etc.

Complications

Macrocytosis does not itself lead to complications.

Prognosis Prognosis ( Greek: πρόγνωσις "fore-knowing, foreseeing"; : prognoses) is a medical term for predicting the likelihood or expected development of a disease, including whether the signs and symptoms will improve or worsen (and how quickly) ...

depends on its cause.

References

External links

{{Portal bar, Biology, Medicine Hematopathology Abnormal clinical and laboratory findings for RBCs

Types

Causes

Complications

See also

References

External links