Refractory Anemia Six Months After Roux-en-Y Gastric Bypass
A 34-year-old woman is 7 months after Roux-en-Y gastric bypass; her BMI has fallen from 44 to 27 kg/m². She reports fatigue, cold intolerance, and hair loss. Hemoglobin is 9.6 g/dL, MCV 78 fL, ferritin 6 ng/mL, transferrin saturation 8%, vitamin B12 165 pg/mL, and folate is normal. She takes ferrous sulfate 325 mg twice daily with breakfast, calcium carbonate 1,200 mg with dinner, and omeprazole 40 mg daily for reflux. She eats about 50 g of protein daily and rarely eats red meat. She denies visible bleeding; stool guaiac is negative and CRP is normal. She has no dysphagia or vomiting. She asks whether she needs a blood transfusion or more iron pills.
1. Explain why oral iron is failing and whether transfusion is needed.
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The oral iron is unlikely to correct the deficiency because of both surgical anatomy and drug interactions. After RYGB, the duodenum and proximal jejunum are bypassed, gastric acid is reduced, and iron absorption is impaired. She is also taking ferrous sulfate with breakfast, likely with coffee, tea, or calcium-containing food, and omeprazole reduces the acid needed for iron absorption. Twice-daily dosing can increase hepcidin and reduce fractional absorption; alternate-day dosing may be better for oral iron, but her ferritin of 6 ng/mL with anemia means oral iron is too slow.
Transfusion is not automatically required at hemoglobin 9.6 g/dL without hemodynamic compromise; IV iron is the priority. She needs a workup for blood loss, but the negative stool guaiac and lack of visible bleeding make malabsorption the leading cause.
2. Design a replacement and monitoring plan for iron and B12.
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Plan: give IV iron, such as ferric carboxymaltose or iron sucrose, dosed by weight and hemoglobin per protocol. Recheck CBC, ferritin, and transferrin saturation at 4–8 weeks; do not expect ferritin to normalize immediately. For B12, give 1,000 mcg IM weekly for 4 weeks, then monthly, or use high-dose oral if adherence is reliable; recheck B12 in 3 months. Continue a folate-containing multivitamin.
Oral iron counseling: if used, take on an empty stomach with vitamin C, alternate days, and separate from calcium, PPI, coffee, and tea by at least 2 hours. Do not take calcium carbonate with iron. Monitor for constipation and dark stools. If anemia persists despite IV iron, evaluate for bleeding, celiac disease, or another cause.
3. What changes would you make to her protein intake, PPI, and calcium regimen?
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Protein: 50 g/day is low after RYGB; target about 60–80 g/day or 1.0–1.5 g/kg reference weight, using protein-first meals and supplements if needed. Hair loss is often telogen effluvium from rapid weight loss and low protein or iron, so reassure but treat deficiencies.
PPI and calcium: omeprazole may be appropriate for reflux, but long-term use worsens iron and B12 absorption and may reduce calcium absorption. Reassess the indication and try the lowest effective dose or discontinuation if reflux is controlled. Switch calcium carbonate to calcium citrate, which does not require gastric acid, and separate it from iron. Dietitian follow-up should address red meat tolerance and total intake.