Intrinsic factor is a glycoprotein produced by the parietal cells of the stomach that is required for the absorption of vitamin B12 from the diet. Conditions that impair intrinsic factor production lead to B12 malabsorption and deficiency.
Stomach acids dissociate B12 from food and intrinsic factor binds to it and allows it to be absorbed.
Laboratory findings for B12 deficiency include decreased serum B12 levels, increased methylmalonic acid and megaloblastic anemia. Impaired hemoglobin synthesis associated with B
The consequence of vitamin B12 deficiency, due to intrinsic factor antibodies is pernicious anemia. The condition is referred to as “pernicious” because it is clinically silent initially and only becomes manifest when patients experience generalized symptoms, such as weakness, diminished energy.