Megaloblastic Anemia from Gastric Bypass Surgery
Gastric Bypass Surgery: Vitamin and mineral deficiencies are relatively common long-term
complications in gastric bypass patients, and result from multiple factors including restricted
food intake, inadequate gastric digestion, and inadequate intrinsic factor.
DNA Synthesis: Vitamin B12 is crucial for the synthesis of DNA, which is necessary for the
normal maturation of red blood cells in the bone marrow. In B12 deficiency, DNA synthesis is
disrupted, leading to the production of large, structurally abnormal red blood cell precursors
called megaloblasts. Maong if naay b12 deficiency ma impaired ang dna synthesis maong mo
resulta sa enlarged RBC.
Enlarged RBC: is the inability of the cell's chromatin to mature normally giving the nucleus a
more immature, more fine, looser, and larger appearance than expected compared to that
of the cytoplasm.
Neuronal Myelin: B12 deficiency can also affect the nervous system. Vit B12 acts as a
cofactor for Homocysteine methyltransferase, an enzyme required to maintain integrity of
the neuron sheath, and Methylmalonyl-CoA mutase, an enzyme responsible for myelin
synthesis. Deranged myelin results to paresthesia in the hands and feet experienced by the
patient.
Ineffective Erythropoiesis: the imbalance of erythroid proliferation and differentiation is
characterized by an increase in erythroblast proliferation that fails to differentiate and give
rise to enucleate RBCs thereby resulting in anemia. Ineffective erythropoiesis means the
process of making red blood cells in the body is not working properly. There are too many
immature cells (erythroblasts) that can't turn into mature, functional red blood cells without
a nucleus. This imbalance causes anemia, a condition with too few healthy red blood cells.
To summarize, Vitamin B12, also known as cobalamin, is essential for the production and
maturation of red blood cells, nuclear maturation, and healthy myelin production for
neurons. When there is a deficiency in vitamin B12, the process of DNA synthesis and cell
division in the bone marrow is impaired, leading to the production of abnormally large and
dysfunctional red blood cells.
Enzymes explained further:
(Homocysteine methyltransferase: This enzyme carries out the conversion of homocysteine
to methionine. Methionine is a precursor for S-adenosyl methionine, which is a methyl
donor and is required to maintain the integrity of the neuron sheath. A deficiency of vitamin
B12 disrupts this reaction, which leads to reduced formation of S- adenosyl methionine. This
impairs methylation of myelin basic protein and lipids and leads to damage to the myelin
sheath.
Methylmalonyl-CoA mutase: This enzyme is responsible for converting methylmalonyl-CoA
to succinyl-CoA, which is required for myelin synthesis. Interruption of this step leads to the
accumulation of methylmalonyl-CoA and propionyl-CoA. This, in turn, disrupts the process of
normal myelin synthesis and leads to the accumulation of abnormal fatty acids.)