NURS 711 Week 5 Discussion Board Forum 2 on Anemias Example

Discussion Board Forum 2: Anemias

NURS 711 Advanced Physiology/Pathophysiology, Discussion Board Forum 2

Thread by [Student Name]

The patient and the classmates replied to are composites written for a model discussion.

A composite patient I will call Mr. Daniels is 67, was diagnosed with type 2 diabetes twelve years ago and has taken metformin for nine. At his annual visit he reports more fatigue and numb, tingling feet. It would be easy to blame both symptoms on diabetes. His complete blood count, however, shows a hemoglobin of 11.2 g/dL and a mean corpuscular volume of 104 fL, a mild macrocytic anemia. That combination should make an advanced practice nurse think of vitamin B12.

The mechanism explains why one deficiency causes both problems. Dietary B12 is released from protein in the stomach, binds intrinsic factor secreted by the parietal cells, and is absorbed in the terminal ileum in a calcium-dependent process. Inside cells, B12 is a cofactor in two reactions. In the first, it helps regenerate the form of folate needed to make thymidine for DNA; without it, red cell precursors in the marrow keep making hemoglobin and growing, but their nuclei cannot divide on schedule, so they emerge as large, fragile megaloblastic cells, and many die in the marrow (McCance & Huether, 2019). In the second, B12 converts methylmalonyl-CoA to succinyl-CoA; when it fails, methylmalonic acid accumulates, and abnormal fatty acids are thought to disrupt myelin, which damages peripheral nerves and the posterior and lateral columns of the spinal cord. That is why the same missing vitamin can show up on the blood count as large red cells and in the clinic as numb feet and an unsteady walk. Metformin is thought to lower B12 by interfering with the calcium-dependent absorption in the ileum.

Many guidelines have therefore recommended periodic B12 testing in people taking metformin. A 2026 study challenges that rule. Laugesen et al. (2026) studied 3,958 adults with diabetes in two Danish clinics and defined deficiency strictly, requiring both a low plasma B12 and an elevated methylmalonic acid. Deficiency was present in 2.3% of metformin users and 1.3% of nonusers, and the adjusted prevalence ratio of 1.56 had a confidence interval from 0.92 to 2.63, which includes no difference. In type 2 diabetes alone, the rates were 2.3% and 2.0%. The authors concluded that deficiency was uncommon, that metformin carried no meaningful excess risk and that routine screening may be redundant. Because it captured a single moment in a Danish population with generous B12 intake, so it may not apply to every population, but its strict definition is a strength, since low serum B12 alone often overstates deficiency.

For Mr. Daniels, the question is not routine screening; he has symptoms and a macrocytic anemia, so testing B12 with methylmalonic acid is clearly indicated, along with folate, a reticulocyte count and a peripheral smear. If deficiency is confirmed, oral or intramuscular replacement can reverse the anemia, and earlier treatment gives the nerves the best chance to recover. His foot examination should also include vibration and position sense, not only monofilament testing. Jesus told a parable of a man who found a treasure hidden in a field (English Standard Version Bible, 2001/2016, Matthew 13:44). A clinician who looks closely at a mean corpuscular volume instead of passing over it can find something hidden that changes a patient's life.

Reply to Kayla

Kayla, your post on pernicious anemia explained the autoimmune loss of intrinsic factor very clearly, and I want to add why the diagnosis matters beyond the anemia itself. Hlupeni et al. (2026) reported a 59-year-old man with type 2 diabetes who had taken metformin 2 g daily for more than four years. Mild macrocytosis appeared on routine laboratory work and went unexplored for about a year, until he presented with severe symptomatic macrocytic anemia. The workup revealed pernicious anemia, and surveillance endoscopy found an early-stage gastric adenocarcinoma. The case shows two lessons. First, metformin can become a convenient explanation that stops the search; a clinician who attributes a low B12 to metformin may miss pernicious anemia entirely. Second, the chronic atrophic gastritis behind pernicious anemia raises the risk of gastric cancer, so a confirmed diagnosis should prompt consideration of endoscopic evaluation. A case report proves nothing about frequency, but it shows clearly what is at stake when an abnormal value sits unexamined. It also connects your topic to mine: the patient's metformin use may have delayed the search for another cause, since a low B12 in a metformin user can seem already explained. In primary care, a simple rule may help, which is that macrocytosis gets a documented explanation within a set time rather than a note to recheck next year. Would you include intrinsic factor antibodies in your initial workup for any patient with macrocytosis, or only those whose B12 is low?

Reply to Marcus

Marcus, I agree that peripheral neuropathy in a person with diabetes is usually diabetic, but your post made me think about the patients in whom it is not. Park (2026) described a 66-year-old man with long-standing diabetes and many years of metformin who had a decade of distal tingling and worsening balance, attributed throughout to diabetic neuropathy. A bedside examination found a positive Romberg sign and impaired joint position and vibration sense, a pattern of sensory ataxia pointing to the posterior columns, along with mild macrocytosis without anemia. In a primary care setting without immediate confirmatory testing, empirical B12 replacement was started, and the patient's tingling resolved and his gait improved substantially. The lesson for an advanced practice nurse is that a positive Romberg test and loss of position sense are clues that the spinal cord, not just the peripheral nerves, may be involved, which points toward B12. Proverbs encourages the wise to listen and increase in learning (English Standard Version Bible, 2001/2016, Proverbs 1:5), and the patient's history and examination are where that learning begins. The case also reminds us that neurological damage from B12 deficiency can occur without anemia, so a normal hemoglobin does not rule the deficiency out. In patients like this one, a mildly raised mean corpuscular volume may be the only laboratory hint. Do you routinely check the Romberg sign and position sense in your diabetic foot examinations, or mainly monofilament sensation?

References

English Standard Version Bible. (2016). Crossway. (Original work published 2001)

Hlupeni, A., Melnick, J., Adejola, A., Mohemmed, T., & Chahla, E. J. (2026). Severe macrocytic anemia uncovering pernicious anemia and early-stage gastric adenocarcinoma: A case report. Cureus, 18(7), Article e112800. https://doi.org/10.7759/cureus.112800

Laugesen, K., Abildgaard, A. M., Hoffmann-Lücke, E., Madsen, L. R., Parkner, T., & Knudsen, S. T. (2026). Metformin and vitamin B12 deficiency: A prevalence study. Endocrine Practice. Advance online publication. https://doi.org/10.1016/j.eprac.2026.08.001

McCance, K. L., & Huether, S. E. (2019). Pathophysiology: The biologic basis for disease in adults and children (8th ed.). Elsevier.

Park, J. (2026). Sensory ataxia mimicking diabetic neuropathy in a long-term metformin user: A case report from Korea. Cureus, 18(6), Article e110704. https://doi.org/10.7759/cureus.110704