Micronutrient Deficiencies Bacterial Overgrowth
Definition Early Nutritional Support Long Term Nutritional Support
Micronutrient Deficiencies Bacterial Overgrowth Nutrition Assessment, Intervention and Outcome
Short Bowel Syndrome (SBS) is defined as malabsorption resulting from anatomical or functional loss of a significant length of the small intestine. Most commonly this occurs after bowel resection in the newborn period (i.e., secondary to necrotizing enterocolitis). The amount of bowel that must be lost to produce malabsorption is variable and depends on which section(s) is/are lost, and whether the ileocecal valve is preserved. The normal length of small intestine is approximately 300 to 850 cm for an adult, 200 to 250 cm for an infant over 35 weeks gestation, and approximately 100 to 120 cm for a premature infant, less than 30 weeks gestation. Loss of greater than 80% of the small bowel is associated with increased requirement for parenteral nutrition support, and decreased overall survival. When the ileocecal valve is lost, the resulting bacterial contamination of the small intestine mandates more small intestine for tolerance of oral/enteral feeding.
The small intestine consists of the duodenum, jejunum and ileum. The majority of carbohydrate and protein absorption takes place in the duodenum and jejunum. Fats and fat soluble vitamins, however are absorbed in the ileum. Bile salts are excreted from the liver into the duodenum; these are required for the absorption of long chain fatty acids and fat soluble vitamins in the ileum. Vitamin B12 binds to intrinsic factor (produced in the stomach) and is also absorbed in the terminal ileum. Fluids and electrolytes are predominantly absorbed in the ileum and in the colon. When the duodenum and/or jejunum are resected, the ileum can largely adapt to perform their absorptive functions. However, the duodenum and jejunum cannot adapt to perform the functions of the ileum. Thus, resection of the duodenum or jejunum is generally much better tolerated than resection of the ileum.
The ileocecal valve is the main barrier between the small and large intestine. It helps regulate the exit of fluid and malabsorbed nutrients from the small bowel. It also helps keep bacteria from the large bowel from refluxing into the small bowel. Resection of the ileocecal valve results in decreased fluid and nutrient absorption, and increased bacterial overgrowth in the small bowel (Vanderhoof, 1992).
Immediately after bowel surgery that results in SBS, total parenteral nutrition (TPN) is required until bowel function returns (bowel sounds are detected, and stool is produced). Depending on the severity of short bowel syndrome, full enteral/oral nutrition may be achieved in a matter of weeks to months, or may never be achieved. It is important that a patient be given as much enteral/oral nutrition as possible to facilitate bowel growth and increased absorption of nutrients, and to decrease the deleterious effects of TPN on the liver (Freund, 1991).
Once a child is on full enteral or oral feeds and parenteral nutrition has been discontinued, adequacy of micronutrient absorption becomes a concern. This is especially important when a significant portion of the ileum is missing. Ileal resection can result in fat and fat soluble vitamin malabsorption, consequently it is frequently necessary to give fat soluble vitamins in a water soluble form. These are available in individual vitamin preparations or in a multivitamin preparation (ADEK'S), which contains water and fat soluble vitamins, all in a water soluble form. Additionally, patients with ileal resection may need vitamin B12 injections every 1 to 3 months. It can take from several months to several years for a vitamin B12 deficiency to develop; therefore, long term, regular monitoring of B12 status is necessary.
Trace minerals that may be malabsorbed include calcium (this is often due to vitamin D malabsorption), iron, magnesium, and zinc. These nutrients need to be monitored periodically, especially in the months just after parenteral nutrition is discontinued, and whenever a patient develops a prolonged diarrheal illness or has bacterial overgrowth.
Patients with SBS often have poor intestinal motility and dilated segments of the small intestine. These factors plus absence of the ileocecal valve contribute to the development of bacterial overgrowth, (Stringer, 1995). Bacterial overgrowth is present when the bacteria in the small bowel exceed normal levels. Bacterial overgrowth results in malabsorption by causing inflammation of the bowel wall and deconjugation of bile acids (which results in rapid reabsorption of bile, leaving very little for fat absorption). Symptoms include very foul smelling stools and flatus, bloating, cramps, severe diarrhea, gastrointestinal blood loss, and accumulation of D-lactic acid in the blood. Bacterial overgrowth can be diagnosed by breath hydrogen test either fasting or after an oral glucose load, by aspiration and culture of small bowel contents or by blood test for D-lactic acid. Bacterial overgrowth is treated with oral antibiotics. In many cases it is necessary to give cyclic antibiotics for the first five days of every month. In some patients continuous antibiotics are necessary; in these cases, antibiotics are rotated every two to three months to avoid overgrowth of resistant bacteria (Vanderhoof, 1992).
Conclusion:
SBS in children requires vigilant nutritional care. Those children who are dependent on TPN are generally well monitored. It is easy for those who have advanced to oral/enteral nutrition to fall through the cracks if their parents and health care providers are unaware of the potential nutritional problems associated with significant bowel resection. Children with SBS need long-term regular nutrition monitoring to prevent problems associated with fluid, macro- and micro-nutrient malabsorption. Since they are at high risk for dehydration and bacterial overgrowth, they need prompt medical attention any time they have symptoms of gastroenteritis.
For further reading see Warner and Zeigler, 1993 and Wessel, 1994.
Assessment |
Intervention |
Evaluation/Outcome |
Anthropometrics |
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Measure and plot on appropriate growth chart (for infants born prematurely use "corrected age" until 2 years old):
Determine weight, height (length) and head circumference age. Obtain and plot all previous anthropometrics that are available. Compare current data to previous measurements. Calculate incremental weight gain, linear growth and head circumference growth since last measurements obtained and compare to reference data for age (Guo, 1991). In children over 2 years of age measure:
Calculate:
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If poor weight gain, may need to increase calorie and protein intake, or may need to alter intake to decrease stool or ostomy output. If excessive weight gain, decrease caloric intake (this is most often an issue with patients on parenteral nutrition). If poor linear or head growth with normal weight gain, need to refer back to physician for medical work up of poor growth. Use information from assessment of muscle and fat stores to help in assessment of nutritional status. Concerns:
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Weight, height (length) and head circumference is above 5th percentile for age (or corrected age). Weight for height (length) is within 10th to 90th percentiles. Child is gaining weight and growing at a normal rate for age (or corrected age). Muscle and fat stores are within normal limits for age. |
Nutrient Intake Assessment |
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Obtain diet history or 3- to 7-day food intake records, and analyze for energy and protein. If on parenteral nutrition calculate energy and protein in parenteral nutrition solution, check contents of vitamin and mineral additives. |
Compare intake to DRI for age and to growth and weight gain. Infants and children with SBS who are eating or receiving tube feedings often need greater than the DRI for energy and protein. Infants and children on TPN generally need at least 15% less energy and the same protein as for enteral/oral feeding to achieve optimal growth. It is essential to avoid over-feeding, especially with protein, as over-feeding is associated with TPN-induced liver failure. Children who are dependent on TPN or tube feedings need to receive oral stimulation to prevent aversions to oral feeding. |
Energy and protein intake is adequate to promote growth. |
Stool or Ostomy Output Assessment |
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If stooling through anus, obtain information regarding number and size of stools per day. If child has ileostomy or colostomy, obtain information regarding approximate volume of output each day. |
If output is high, patient needs medical evaluation Patients with SBS are at high risk for malabsorption and dehydration; they may need intravenous fluids. May need to alter feeding to decrease carbohydrate and/or long chain fats. Infants may need to switch from a complete formula to a modular formula so that carbohydrate and fat content can be manipulated. Child may have bacterial overgrowth and need antibiotics. If severe, may need TPN until bacterial overgrowth resolved. Child may have a viral gastroenteritis and therefore needs careful management of fluid status until gastroenteritis resolves. |
Stool or ostomy output is less than 30-35 mL/kg/day. |
Laboratory Assessment |
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Once on enteral nutrition, the risk of nutrient deficiencies due to malabsorption is high. Specific nutrients must be monitored regularly. Monitor serum levels of vitamins A, E, and D; calcium; phosphorus alkaline phosphatase; magnesium, and zinc up to once every 4 weeks from the time that parenteral nutrition is discontinued until all are within normal limits for 2 months. Once stable, measure every 6 to 12 months. Monitor serum level of vitamin B12 every 6 to 12 months for 3 to 5 years. (It can take years for vitamin B12 deficiency to develop) |
If intestinal loss is in ileum, give ADEKs multivitamin (1 mL liquid/day for infants < 1 year; 2 mL liquid/day for children 1-3 years; 1 chewable tablet per day for children 3-10 years; 1-2 chewable tablets per day for children >10 years). If deficiency of vitamin A, give additional vitamin A in water soluble form (Aquasol A). Recheck levels every 1-2 weeks while giving high doses of vitamin A to avoid toxicity. If deficiency of vitamin E, give additional vitamin E in water soluble form (Aquasol E or Liqui-E). Recheck levels every 2-4 weeks to avoid vitamin E excess. If deficiency of vitamin D, give Calcitriol, (Rocaltrol), and make sure child is receiving at least DRI of calcium and phosphorus. Check serum calcium at least weekly as long as Calcitriol is given to monitor for vitamin D toxicity. If deficiency of magnesium, give Magnesium-Protein Complex If deficiency of zinc, give zinc supplement Once vitamin B12 levels are in the low normal range, begin intramuscular shots of vitamin B12 (Cyanocobalamin) every 1 to 3 months. Dosages for vitamin and mineral supplements will vary depending on a child's age, size, and degree of deficiency. Consult the child's physician and pharmacist for appropriate dosage of vitamin and/or mineral to treat deficiency. |
Vitamin A, vitamin E, vitamin D, vitamin B12, calcium, phosphorus, alkaline phosphatase, magnesium and zinc all within normal limits (use normal values given by laboratory where blood is analyzed). |