Parenteral nutrition in patients with inborn errors of metabolism - a therapeutic problem

 

Though parenteral nutrition (PN) administration can be effective in improving nutritional status and promoting positive outcomes in patients with severe malnutrition and for those undergoing intensive treatments, its use has been limited in its application to treat inborn errors of metabolism. The fundamental concerns of PN administration in cases involving inborn errors of metabolism are based on the notion that when complicated with other disorders PN formulas are not prepared to appropriately manage these metabolic conditions (Kaluzny et al., 2014). Poznan University of Medical Sciences researchers recently discussed the difficulty of treating metabolic diseases whereby PN is limited. These researchers have addressed four cases in which PN is found to be difficult to administer: Long-chain Hydroxyacyl-CoA Dehydrogenase (LCHAD) Deficiency Associated with Necrotizing Enterocolitis, Short-chain Dehydrogenase (SCAD) Deficiency associated with Congenital Heart Disease, Phenylketonuria (PKU) associated with Rhabdomyosarcoma, and Tyrosinemia Type 1 complicated with Encephalopathy. The first two cases are classified as β-oxidation disorders. Disorders associated with fatty-acid oxidation appear to be caused by mutations in a gene sequence. This gene mutation in turn can lead to enzyme shortages and deficits.  

LCHAD and SCAD deficiencies are characterized by the body’s inability to breakdown certain fats into energy. The optimal treatment for these disorders require diet restrictions and metabolic control (Gillingham et al., 2003). Dietary treatment for LCHAD requires a low-fat, high-carbohydrate diet with limited LCT intake (approx. 10% of total energy), supplementation with MCT (approx. 10-20% of total energy intake) and avoidance of fasting (Gillingham et al., 2003; Kaluzny et al., 2014). Dietary treatment for SCAD is similar. A patient with PKU is unable to synthesize tyrosine due to deficiency in the activity of or the inactivation of the enzyme phenylalanine hydrolase. A life-long adherence to a low-phenylalanine diet is required. Protein foods (i.e., chicken, poultry, steak, fish, cheese, soy products, eggs, high-protein pastas and breads) cannot be eaten on a phenylalanine controlled diet. Medications and any foods that contain aspartame also should be avoided. Doing so lessens the chance of increasing blood phenylalanine and therefore decrease the risk of neurological damage and death.

PN is an alternative approach of nutritional support when enteral feeding is not feasible. Although PN is an effective means to deliver nutrients in the setting of metabolic diseases, the needs of patients are not always met because challenges of contraindications and coincidences with inborn errors of metabolism limit the use of PN. As suggested by Kaluzny et al. (2014) disorders associated with “fatty acid oxidation defects and aminoacidopathies” are often difficult due to contraindications in the formulas proposed for the disease. If the patient presents with enterocolitis, congenital heart disease, rhabdomyosarcoma, or encephalopathy, etc. following diagnosis of an inborn error of metabolism, the main goal is to deliver adequate nutrition via intravenous infusions (i.e., high-dose glucose infusions) (Kaluzny et al., 2014). Given the fact that PN formulas “contain amino acids which are prohibited in aminoacidopathies or have incorrect lipid profiles in fatty acid oxidation disorders” (Kaluzny et al., 2014), dietitians may need to reconsider the use of certain intravenous infusions to avoid complications in patients with inborn errors of metabolism and associated diseases/conditions.

References

Kaluzny, L., Szczepanik, M., Siwinska-Mrozek, Z., Borkowska-Klos, M., Cichy, W., & Walkowiak, J. (2014). Parenteral nutrition in patients with inborn errors of metabolism – a therapeutic problem. European Review for Medical and Pharmacological Sciences 18, (11), 1579-1582.

http://www.europeanreview.org/article/7452

Gillingham, MB., Connor, WE., Matern, D., Rinaldo, P., Burlingame, T., Meeuws, K., & Harding, C. (2003). Optimal dietary therapy of long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency. Molecular Genetics and Metabolism 79 (2), 114-123. doi: 10.1016/S1096-7192(03)00073-8

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2813192/

 

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