I am treating a 44-year-old Filipina who has iron deficiency anemia. Her RBC count, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and mean corpuscular volume are low and her hematocrit/hemoglobin is borderline low. Her ferritin rose from 2 to 3 ng/mL after two months of ferrous sulfate t.i.d. and vitamin C 500 mg daily. A recheck of her labs found slight elevations in her erythrocyte sedimentation rate (ESR) and her aminotransferase levels. The patient was referred to a GI specialist for workup of celiac sprue. No colonoscopy or biopsy was done, and she was told her labs were unremarkable. Despite adherence to the recommended iron supplementation, she continues to be anemic and iron-deficient and complains of fatigue and dizziness. Tests for thalassemia and B12 deficiency were negative. The patient is otherwise healthy, active, and without depression. What should I do next?

This patient is clearly iron-deficient. Other than menstrual losses in a premenopausal woman, the most common cause of iron deficiency is loss via the GI tract or inability to absorb iron from the GI tract. The elevated ESR and increased liver enzymes are cause for concern. All should be rechecked. She definitely requires a colonoscopy and upper endoscopy to rule out a lesion (e.g., a malignancy, inflammatory bowel disease, or peptic ulcer disease). During the upper endoscopy, a biopsy from the duodenum should be carried out to rule out celiac disease. I am unsure whether a gastroenterologist’s saying that her labs were “unremarkable” translates into negative celiac serology; however, it is important to keep in mind that low serum immunoglobulin A levels can result in a falsely negative celiac panel. If the studies are unremarkable, she should undergo a capsule endoscopy to rule out small-intestinal lesions. Stool specimens can be sent to test for the presence of fat (Sudan stain) and determine if she has malabsorption. In addition, consider a D-xylose study—in which the patient drinks D-xylose (a sugar not found in nature) and undergoes subsequent blood draws to see if the sugar was absorbed. If she has malabsorption, imaging (CT or ultrasound) to visualize the pancreas and liver should be strongly considered to rule out a lesion. If all the studies are negative, refer the patient to hematology to consider IV iron infusions.
—Bruce D. Askey, MSN, CRNP