Anemia is a condition of low red blood cell counts. One way to classify anemia is by how it looks under the microscope. Macrocytic anemias show large red blood cells. The type of anemia helps narrow down the cause so it can be fixed. Homocysteine is a chemical that can be elevated in macrocytic anemia. The diagnosis and treatment of anemia and other diseases should be done in consultation with a health care professional.
Causes
Microcytic and normocytic anemias have numerous causes, but macrocytic anemias have few. Slightly larger red blood cells are associated with alcoholism and a few other conditions. The primary causes of macrocytic anemias are two specific vitamin deficiencies: vitamin B12, or cobalamin, and folate. Both of these deficiencies have effects on the level of homocysteine.
Megaloblastic Anemia
Megaloblastic anemia is a specific type of macrocytic anemia and the one that is caused by B12 and folate deficiency. It is associated with problems in DNA synthesis in red blood cells, due to the low levels of B12 and folate, which are required for appropriate DNA metabolism. Enzymes required for DNA synthesis in the bone marrow become impaired without B12 and folate. The cells cannot divide at the right time and instead continue to grow to a large size.
Elevated Homocysteine
Enzymes help chemical reactions to occur. Folate and vitamin B12 bind to specific enzymes, allowing them to work. Both folate and vitamin B12 are needed to convert homocysteine into methionine, which is in turn needed for DNA synthesis and other functions. An absence of either vitamin blocks the conversion of homocysteine to methionine, leading to a buildup of homocysteine.
Diagnosis
The diagnosis of anemia may be incidental, during a routine blood test. Since red blood cells carry oxygen to the tissues, and the red color from hemoglobin in the cells imparts color to the tissues, low levels of red cells can lead to weakness and fatigue from low oxygen reserve and pallor of the skin, eyes and mucous membranes. In addition, B12 deficiency causes nerve problems that manifest as tingling and sensation problems. Other diagnostic processes can help narrow the cause.
Treatment
The treatment of megaloblastic anemia involves discovering the source of the deficiency and supplementing with B12 and folate. Some deficiencies may be from a lack of dietary intake, but other times medications can be responsible.
References
- "Harrison's Principles of Internal Medicine"; Anthony S Fauci et al.; 17th Ed 2008
- "Robbins and Cotran Pathologic Basis of Disease"; Vinay Kumar et al.; 8th Ed 2009
- "Lehninger Principles of Biochemistry"; David L. Nelson and Michael M. Cox; 4th Ed 2004
