Chapter 15: Manganese and Parenteral Nutrition

For more than four decades, parenteral nutrition has provided life-sustaining macronutrient and micronutrient nutritional therapy for patients unable to tolerate enteral nutrition. Despite its critical importance and widespread use, the optimal dosing of various parenteral nutrition additives is unknown, posing a threat to human health. This knowledge gap is particularly acute for the trace element manganese (Mn), which is routinely added to parenteral nutrition solutions used for children and adults. Mn is an essential metal required for normal growth and development. However, excessive parenteral dietary Mn can be neurotoxic, causing a constellation of psychological and neurological symptoms known as manganism. Mn neurotoxicity is a well-described entity in adults receiving prolonged parenteral nutrition. Infants and children requiring parenteral nutrition represent an understudied and particularly vulnerable population whose susceptibility to the toxic effects of excess Mn is complicated by their developmental stage. This chapter will review the risk factors for the potential adverse effects of parenteral Mn when provided in excessive amounts, or when normal metabolism or excretion is altered by an underlying medical condition or by developmental immaturity. The need for the establishment of safe guidelines is emphasized and areas for potential research are highlighted.