A 48-year-old woman with a 10-year history of rheumatoid arthritis (RA) presents to the clinic with increasing fatigue and pallor. Her joint symptoms are being managed with methotrexate, but she reports difficulty performing daily activities due to weakness. On examination, her vital signs are stable, but conjunctival pallor is evident. Laboratory investigations reveal a hemoglobin level of 9.5 g/dL, mean corpuscular volume (MCV) of 85 fL, mean corpuscular hemoglobin concentration (MCHC) of 32 g/dL, normal serum ferritin, and reduced serum iron levels.
What type of anemia is most likely associated with her condition?
A. Normochromic normocytic
B. Sideroblastic
C. Megaloblastic
D. Aplastic anemia
E. Dietary
Correct Answer: A. Normochromic normocytic
Explanation:
Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease often associated with anemia of chronic disease (ACD). The anemia in ACD is typically normochromic normocytic, meaning the red blood cells are normal in size (MCV) and hemoglobin concentration (MCHC).
In RA, persistent inflammation leads to elevated levels of proinflammatory cytokines such as interleukin-6 (IL-6). These cytokines increase hepcidin synthesis in the liver, a key regulator of iron metabolism. Hepcidin inhibits iron release from macrophages and decreases intestinal iron absorption, resulting in a functional iron deficiency despite normal or elevated ferritin levels (a marker of stored iron). The bone marrow remains capable of producing red blood cells, but iron availability is insufficient for effective erythropoiesis.
Key features supporting normochromic normocytic anemia in this patient include:
- Normal MCV (85 fL) and MCHC (32 g/dL).
- Low serum iron with normal ferritin, consistent with inflammation-driven iron sequestration.
- Absence of vitamin B12, folate deficiency, or bone marrow suppression.
Management focuses on controlling the underlying RA inflammation, which may improve anemia. In refractory cases, erythropoiesis-stimulating agents or iron supplementation (IV in most cases) might be required.
B. Sideroblastic Anemia
This type of anemia is characterized by defective hemoglobin synthesis due to abnormal iron incorporation into heme. It is associated with ringed sideroblasts in the bone marrow, which are not observed in RA. Causes include myelodysplastic syndromes, lead poisoning, and certain drugs, but it is unrelated to chronic inflammation.
C. Megaloblastic Anemia
This results from vitamin B12 or folate deficiency, leading to impaired DNA synthesis and the production of macrocytic red blood cells (high MCV). Although methotrexate, a drug used in RA, can cause folate deficiency, there is no evidence of macrocytosis or hypersegmented neutrophils in this case.
D. Aplastic Anemia
Aplastic anemia involves pancytopenia (low counts of all blood cell lines) due to bone marrow failure. This patient does not have leukopenia or thrombocytopenia, ruling out this diagnosis.
E. Dietary Anemia
Dietary deficiencies such as iron deficiency anemia often cause microcytic hypochromic anemia (low MCV and MCHC), which is not consistent with this patient’s laboratory findings. Additionally, the normal ferritin level excludes iron deficiency.