Postgastrectomy Nutrition / Rogers   133
should be based on patient comfort and compliance. Parenteral B12 supplementation begins with 1,000 mcg every day for 1 week, followed by 1,000 mcg every week for 4 weeks. To maintain normal B12 levels, monthly 1,000 mcg injections may be required for life. Oral B12 supplementation requires 1,000-2,000 mcg daily.67 Little information exists regarding folate deficiency after partial or total gastrectomy. Although folate is absorbed in the proximal small bowel and rapid transit through this area is possible after gastrectomy, folate deficiency due to malabsorption has not been documented. If suspected, folate deficiency should be diagnosed with red blood cell folate, not serum folate.4 To correct folate deficiency, 5 mg of folate should be given daily.4 Vitamin B12 is needed to activate folate, so supplementing folate with a concurrent B12 deficit will only exacerbate the B12 deficiency.68 Tovey et al5 found that 10 years after gastrectomy, iron deficiency was the most common nutrient deficiency. Iron deficiency usually occurs 10 years before the onset of B12 deficiency.5 Most iron absorption occurs along the duodenal and upper jejunum mucosa.69 After gastrectomy, bypass of the duodenum and/or rapid transit of food particles through the intestine can lead to iron deficiency.65 Additionally, gastric acid aids the conversion of ferric ions to ferrous ions, which are more easily absorbed.69 The decreased acid production following gastrectomy impedes this process. Serum ferritin, a storage protein for iron, will accurately reflect iron stores in a nonacute phase setting.3,70 Iron deficiency is best treated with 200 mg of oral elemental iron daily. A 200-mg tablet of ferrous sulfate provides 67 mg of elemental iron. Therefore, it should be given 3 times per day, 6 hours apart, and with the addition of vitamin C to enhance absorption.3,68 One case report revealed villi flattening on jejunal biopsies in a patient with anemia unresponsive to oral iron therapy. After the administration of parental iron over 4 weeks, the villous atrophy resolved and the patient’s anemia continued to improve with the use of oral iron supplementation.69 Patient compliance is often an issue with iron therapy because of side effects including nausea, abdominal pain, constipation, or diarrhea.3 Consequently, frequent encouragement to increase intake of iron-rich foods may be necessary. The heme form of iron is more available than the nonheme form of iron. Absorption of nonheme iron is enhanced by ascorbic acid (vitamin C) and amino acids and inhibited by phosphates, phytates, oxalates, and tannates.69 Heme and nonheme iron are found in meat, fish, and poultry. However, only nonheme iron exists in eggs, grains, vegetables, and fruits.71
osteopenia in 44% of Billroth I patients, 27% of Billroth II patients, and 44% of total gastrectomy patients. Bisballe et al73 found that 18% of postgastrectomy patients had osteomalacia. However, when Liedman et al74 compared total gastrectomy patients with age- and sex-matched controls, they could not demonstrate any divergence. Even though 25% of the total gastrectomy patients had osteoporosis approximately 8 years after surgery, the results indicate that this is more likely due to aging rather than a consequence of postsurgical sequelae.74 Although the cause of bone disease following gastrectomy is also unclear, several mechanisms have been suggested. Decreased dietary intake of calcium and vitamin D may play a role.3,10 Malabsorption of calcium may also be a factor because calcium is primarily absorbed in the duodenum, which may be bypassed because of surgical reconstruction or rapid transit.75 Additionally, fat malabsorption may lead to the formation of insoluble calcium soaps.75 Alterations in bone-related hormones may lead to bone disease although serum parathyroid hormone levels in postgastrectomy patients have ranged from subnormal to normal.75 Malabsorption of vitamin D has been discussed as a possible mechanism, but neither calcium nor vitamin D malabsorption has been proven in postgastrectomy patients.75 In fact, when Bisballe et al73 found osteomalacia in 18% of postgastrectomy patients, the majority if the patients had normal serum calcium and 25-hydroxyvitamin D levels (25-OHD).3 Despite the contradictions regarding incidence and cause of bone disease post gastrectomy, monitoring bone mineral density via dual-emission X-ray absorptiometry scans and ensuring that postgastrectomy patients consume adequate amounts of calcium rich foods is beneficial. This is especially true given that the majority of these surgical patients are elderly. For patients with confirmed bone disease, 1,500 mg of calcium daily is recommended.3 Additionally, as more information emerges regarding suboptimal 25-OHD levels in the healthy population, monitoring serum 25-OHD post gastrectomy seems reasonable. The current guidelines from the Institute of Medicine recommend a 25-OHD level of 20 ng/mL to maintain good bone health.76 For men and women under the age of 51, 600 international units of vitamin D daily should be sufficient to meet this goal.76 For those over the age of 71, 800 international units of vitamin D daily is recommended.76 The Institute of Medicine cautions that the risk for harm increases in doses of vitamin D beyond 4,000 international units daily.76
Implications for Clinical Practice Most studies analyzing patients post gastrectomy, including those cited in this review, have a small sample size, and few involve randomized controlled trials.* Additionally,
Bone Disease The incidence and cause of bone disease after subtotal or total gastrectomy are not clear. Zittel et al72 reported
*5, 9, 16, 53, 62, 66, 74, 77, 78
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