Differential Diagnosis
- Single most likely diagnosis
- Decrease serum ferritin level: This is the most likely finding given the patient's symptoms of fatigue, pallor, and low hemoglobin level. A decrease in serum ferritin level is indicative of iron deficiency anemia, which is a common condition in patients with chronic diseases like rheumatoid arthritis.
- Other Likely diagnoses
- Elevated total iron binding capacity (TIBC) within normal limits is not a likely finding, but elevated TIBC is often seen in iron deficiency anemia.
- Elevated homocysteine level: This could be seen in patients with vitamin B12 or folate deficiency, which can also cause anemia. However, the patient's symptoms and low hemoglobin level make iron deficiency anemia more likely.
- Elevated serum unconjugated bilirubin level: This could be seen in patients with hemolytic anemia, but the patient's symptoms and lack of other signs of hemolysis make this less likely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Decrease erythrocyte sedimentation rate (ESR): While a decrease in ESR is not typically associated with anemia, a significantly elevated ESR can be seen in chronic diseases like rheumatoid arthritis. However, a decrease in ESR is not a typical finding in anemia.
- Vitamin B12 deficiency: This is a potentially deadly diagnosis if missed, as it can cause neurological symptoms and anemia. However, the patient's symptoms and low hemoglobin level make iron deficiency anemia more likely.
- Rare diagnoses
- Sulfasalazine-induced hemolytic anemia: This is a rare but potentially life-threatening condition. Sulfasalazine can cause hemolytic anemia in some patients, especially those with glucose-6-phosphate dehydrogenase (G6PD) deficiency.
- Other rare causes of anemia, such as myelodysplastic syndrome or paroxysmal nocturnal hemoglobinuria (PNH), are less likely given the patient's symptoms and medical history.