Alterations in Oxygen Transport
Deb Smith, age fifty-six, came to her nurse practitioner (NP) with fatigue, pallor, dyspnea on exertion, and palpitations. Her laboratory report indicates that her hematocrit, hemoglobin, and reticulocyte counts are low; that her MCV is high; and that her MCH and MCHC are normal. Her diagnosis is pernicious anemia.
Answer the following questions regarding Deb’s anemia and provide the pathophysiology associated with the body’s response to this disease process.
- Why should Deb’s NP ask her about paresthesia and ataxia?
- Why did her NP prescribe vitamin B12 by intramuscular injection rather than orally?
- What causes pernicious anemia?
- What are the technical terms that describe an anemia with high MCV and normal MCH?
Expert Solution Preview
Introduction: In this case scenario, a patient named Deb Smith is diagnosed with pernicious anemia. As a medical professor, I will answer the following questions related to Deb’s condition and provide the associated pathophysiology.
1. Why should Deb’s NP ask her about paresthesia and ataxia?
Deb’s NP should ask her about paresthesia and ataxia because they are the common neurological symptoms associated with pernicious anemia. Pernicious anemia is caused by the deficiency of vitamin B12, which is essential for the proper functioning of nerve cells. The deficiency of vitamin B12 affects the myelin sheath, which covers and protects the nerve fibers. As a result, the damaged myelin sheath causes neurological symptoms such as paresthesia (tingling or numbness in the hands and feet) and ataxia (loss of control over body movements).
2. Why did her NP prescribe vitamin B12 by intramuscular injection rather than orally?
Deb’s NP prescribed vitamin B12 by intramuscular injection rather than orally because pernicious anemia is caused by the deficiency of intrinsic factor (IF), which is essential for the absorption of vitamin B12 in the small intestine. Oral intake of vitamin B12 will not be effective as the stomach acidity and lack of IF in the intestine prevent the absorption of vitamin B12. Therefore, intramuscular injection of vitamin B12 bypasses the requirement of IF and ensures adequate absorption of the vitamin in the body.
3. What causes pernicious anemia?
Pernicious anemia is caused by the deficiency of intrinsic factor (IF), a protein produced in the stomach that is essential for the proper absorption of vitamin B12. The autoimmune response against the parietal cells in the stomach lining, responsible for the secretion of IF, causes impaired absorption of vitamin B12 in the small intestine. As a result, the deficiency of vitamin B12 leads to the impairment of red blood cell production in the bone marrow, causing anemia.
4. What are the technical terms that describe an anemia with high MCV and normal MCH?
An anemia with high mean corpuscular volume (MCV) and normal mean corpuscular hemoglobin (MCH) is known as macrocytic-normochromic anemia. The high MCV indicates the presence of larger and fewer red blood cells, whereas the normal MCH indicates adequate hemoglobin content in the red blood cells. Pernicious anemia is an example of macrocytic-normochromic anemia.
