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Folate in blood formation
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Folate, which is vitamin B9, is used to build DNA, the instruction manual that every new cell has to copy before it divides. That is why the bone marrow, the factory for blood cells, depends on it.
When folate runs short, the factory falls out of step. The nucleus of the cell, which is where the DNA sits, matures slowly because it is short on parts, while the cytoplasm, which is the rest of the interior, keeps its normal pace. It is a construction site where the bricks arrive on time and the blueprints arrive late. The result is oversized erythroblasts, which are red blood cells still being formed, and many of them die inside the marrow itself without ever getting out. That is what megaloblastic anemia means: anemia with large cells.
The ones that do get out reach the bloodstream larger than normal. And the smear, which is a drop of blood spread out and looked at under the microscope, shows another clue: hypersegmented neutrophils, white blood cells whose nucleus looks split into more lobes than it should have.
In brief
Folate, vitamin B9, is essential for DNA synthesis and for making red blood cells, so the bone marrow depends on it.
Without folate the nucleus matures slowly while the cytoplasm keeps its normal pace, and the result is large erythroblasts that die inside the marrow: this is megaloblastic anemia.
A construction site where the bricks arrive on time and the blueprints arrive late.
The red blood cells that do reach the bloodstream are large, and the smear shows hypersegmented neutrophils.
Sources (2)
- National Center for Biotechnology Information, StatPearls PublishingFolic Acid Deficiency, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingAnemia, StatPearlsPublished
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