Vitamin B12 malabsorption after jejuno-ileal bypass surgery.

Six patients subjected to jejuno-ileal bypass surgery for obesity were studied for vitamin B12 absorption by the use of the Schilling test, together with measurement of the serum B12 level preoperatively and at 2, 6, 12, 18 and 24 months after the operation. During the follow-up period of 2 years, the serum vitamin B12 level gradually declined to abnormally low values. A postoperative fall of the originally normal vitamin B12 absorption to abnormal values was found. Oral administration of tetracycline resulted in a transitory improvement of the results by the Schilling test, but after its discontinuation serve vitamin-B12 malabsorption was again demonstrable. The importance of parenteral vitamin B12 administration after jejuno-ileal bypass surgery is emphasized.