Nutritional deficiencies

Hyperparathyroidism, due to inadequate absorption of calcium, may occur in over 30% of GBP patients. Calcium is primarily absorbed in the duodenum, which is bypassed by the surgery. Mostpatients can achieve adequate calcium absorption by supplementation with Vitamin D and Calcium Citrate (carbonate may not be absorbed - it requires an acidic stomach, which is bypassed).

Iron frequently is seriously deficient, particularly in menstruating females, and must be supplemented.

Again, it is normally absorbed in the duodenum.

Ferrous sulfate can cause considerable GI distress in normal doses; alternatives include Ferrous fumarate, or a chelated form of iron. Occasionally, a female patient develops severe anemia, even with supplements, and must be treated with parenteral iron.

Vitamin B-12 requires intrinsic factor from the gastric mucosa to be absorbed. In patients with a small gastric pouch, it may not be absorbed, even if supplemented orally, and deficiencies can result in pernicious anemia and neuropathies. Sublingual B-12 appears to be adequately absorbed.

Thiamine deficiency (also known as beriberi) will, rarely, occur as the result of its absorption site in the jejunum being bypassed. This deficiency can also result from inadequate nutritional supplements being taken post operatively.

Protein malnutrition is a real risk. Some patients suffer troublesome vomiting after surgery, until their GI tract adjusts to the changes, and cannot eat adequate amounts even with 6 meals a day. Many patients require protein supplementation during the early phases of rapid weight loss, to prevent excessive loss of muscle mass.