Patient A is a college student who has become increasingly tired over the last six months. She thought it was because of her tough schedule, but she thought she should see a doctor since she noticed tingling in her feet. Patient A also has hyperparathyroidism, an autoimmune disorder that affects 100,000 people in the U. S. every year. She is not a vegetarian and eats milk, eggs and meat - all great sources of B12. The doctor ran some blood work and found very low levels of B12. The patient also had parietal cell antibodies present in her blood. What do you think is the cause of her B12 deficiency? Why is her body not able to absorb the necessary B12?