When a patient’s nutritional requirements are assessed, the focus often is on calories and protein intake. But recognizing potential vitamin deficiencies and providing adequate micronutrients to patients receiving TPN is of critical importance.3
Certain conditions predispose patients to hypovitaminosis. Because vitamins are pivotal in maintaining cellular integrity, deficiencies can significantly impair organ function and recovery from illness.2
Factors contributing to vitamin deficiencies include:2,3
- Chronic diseases
- Advanced age
- Medications
- Trauma
- Substance abuse
Chronic Diseases
Studies indicate that deficiencies in micronutrients due to disease can compromise immune function and lead to morbidity and mortality.2,3 Diseases associated with hypovitaminosis include:
- End-stage renal disease. ESRD patients can be deficient in thiamine, riboflavin, niacin, folate, biotin, and vitamins A, C, B6, and B12. Recent studies concluded that patients undergoing renal replacement therapy had reduced concentrations of vitamin C, vitamin E, folic acid, and pyridoxal phosphate (metabolized and phosphorylated form of vitamin B6).2,3
- End-stage liver disease. Hypovitaminosis has been noted in end-stage liver disease, including chronic active hepatitis, primary sclerosing cholangitis, primary biliary cirrhosis, and acute or subacute hepatitis.2,3
- HIV and AIDS. Evidence of folate and vitamin B12 deficiency has been reported in HIV-infected individuals.2
- Cancer. The potential for overall malnutrition, as well as for micronutrient deficiencies, is particularly high in certain cancer patients due to impaired absorption and heightened needs resulting from surgery, chemotherapy, and radiation therapy. Serum levels of vitamins B1, B2, B6, and niacin are decreased in up to 40% of cancer patients.2,3
- Chronic inflammation. Patients with systemic inflammatory response syndrome (SIRS) have experienced decreased levels of vitamins A, B6, C, and E.3
- Irritable bowel disease. Deficiencies of water-soluble vitamins – especially folate, vitamin B12, and vitamin C – can occur in patients with inflammatory bowel disease. Patients with Crohn’s disease who have fistulous tracts may have especially low serum vitamin C levels.2,3
- Short-bowel syndrome. Nutrients that normally have an enteropancreatic or enterohepatic circulation may be lost in large amounts in patients with short-bowel syndrome, since endogenous intestinal secretions are not effectively reabsorbed. Vitamins with enteric cycles that can be disrupted in these patients include fat-soluble vitamins, vitamin B12, and folate.2,3
Advanced Age
Elderly patients often have an inadequate intake of vitamins in their diet and also may take medications that can promote vitamin deficiency. Some of the more prevalent vitamin deficiencies among older persons include vitamins D, C, B12, B6, and folate.1,3
Factors in this population that increase risk for hypovitaminosis include depression, dementia, poor dentition, substance abuse, polypharmacy, functional limitation, and social isolation.1
Medications
Medications can promote vitamin deficiency by inhibiting absorption, interfering with metabolic pathways, adsorbing vitamins, or promoting excretion.3 Medications commonly used to treat infection, inflammation, cancer, diabetes, gastrointestinal dysfunction, and fluid retention can contribute to the risk for hypovitaminosis.4
Examples of drug-mediated effects on micronutrient status:4
- Dextroamphetamine, fenfluramine, levodopa may induce anorexia and can affect potentially all micronutrients.
- Cholestyramine can decrease absorption and can adsorb vitamin D and folate.
- Omeprazone induces modest bacterial overgrowth and decreases gastric acid, thereby impairing absorption of vitamin B12.
- Sulfasalazine, methotrexate can impair folate absorption and/or inhibit folate-dependent enzymes.
- Isoniazid impairs utilization of vitamin B6.
- NSAIDs can affect iron levels and lead to gastrointestinal blood loss.
- Penicillamine can affect zinc levels and increase renal excretion.
Trauma
In burn patients, diminished intake frequently leads to vitamin deficiency, and rapid fluid loss and impaired absorption can also be a significant cause of fat-soluble vitamin deficiency. Burn patients require additional amounts of zinc and vitamins A and C.3
Multi-trauma victims of automobile and other accidents receiving TPN on a short-term basis are at risk for hypovitaminosis despite the fact that they are obtaining the calories they need. Vitamins are necessary for wound healing; poor healing may indicate a vitamin deficiency. 3
Substance Abuse
Substance abuse often is associated with poor nutrition and interrupted metabolic pathways. Patients who abuse alcohol often are deficient in thiamine and folic acid, but it is likely that their diet is lacking other micronutrients as well. TPN patients with a history of alcohol abuse are particularly susceptible to Wernicke's encephalopathy and Korsakoff's psychosis caused by deficiency of B-complex vitamins, especially thiamine and B12.2,3
Summary
The interrelationships of vitamins make it imperative to maintain all vitamin levels, since the lack of one vitamin can affect the availability or function of another. In hypovitaminosis, biochemical systems can be affected before physical manifestations appear.3
Left untreated, vitamin deficiencies can contribute significantly to morbidity and mortality. To reduce the risk, clinicians need to expand their nutritional assessment beyond an evaluation of calories and protein and consider factors that may increase the risk for hypovitaminosis.
References:
1. Berg M, Jensen G. Micronutrient Deficiencies Among Older Persons. aaiPharma Newslines, Apr 2003. Available at: http://www.imakenews.com/mvius/index000030139.cfm. Accessed January 2004.
2. Bistrian B. The Need for Parenteral Vitamin Supplementation in Critically Ill Patients. aaiPharma Newslines, September 2003. Available at: http://www.imakenews.com/mvius/index000036024.cfm. Accessed January 2004.
3. Fuhrman MP. Identifying Your Patient’s Risk for a Vitamin Deficiency. Nutr Clin Prac. 2001;16:S8-S11
4. Goldman, ed. (2000). Cecil Textbook of Medicine, 21st ed., pp. 1172-1178. Philadelphia: W.B. Saunders Company.
5. US Centers for Disease Control (1997). Lactic Acidosis Traced to Thiamine Deficiency Related to Nationwide Shortage of Multivitamins for Total Parenteral Nutrition. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/00047949.htm. Accessed January 2004.