Answer: D. Iron deficiency after Roux-en-Y gastric bypass can occur as early as two months after surgery or at any point in life after Roux-en-Y gastric bypass. The incidence of iron deficiency may be higher in menstruating females or those who become pregnant after the procedure. The recommended dose of iron for s/p Roux-en-Y gastric bypass patients is 36 to 65 mg elemental iron daily. Menstruating women should be taking 100 mg elemental iron daily. If iron deficiency occurs after Roux-en-Y gastric bypass, doses of up to 300 mg oral iron daily may be needed. In some cases (especially for menstruating women) intravenous iron may be warranted.