Class of 2013 Abstract / Specific Aims: Trace elements such as manganese are added into parenteral nutrition formulations to prevent or treat trace elements deficiencies. Excessive amounts of certain trace elements added to parenteral nutritional formulations can cause potential adverse effects. The purpose of this study was to evaluate whole-blood manganese concentrations obtained in patients prescribed parenteral nutrition for more than 30 days. The manganese concentrations obtained were evaluated based on the duration and amount of manganese prescribed in the parenteral nutritional formulations.. Methods: In this IRB approved project, adult patients prescribed parenteral nutrition for at least 30 consecutive days at an academic medical center or through the outpatient healthcare system between January 2007 and December 2011 were evaluated. Subjects were excluded if no manganese concentrations were obtained while parenteral nutrition was prescribed. Manganese concentrations were grouped by duration that trace elements were added to parenteral nutrition formulations as < 30 days, 30-90 days, 90-365 days, and >365 days. A fifth group of manganese concentrations were evaluated if they were obtained when manganese was not added to the parenteral nutritional formulation for at least 90 days. Data collected included demographic information, reason for initiation and discontinuation of parenteral nutrition, reason for long-term parenteral nutrition, duration of parenteral nutrition, duration and timing of other nutrient sources, amount prescribed and timing of trace elements, trace element concentrations, and documentation of potential manganese toxicity in medical records. A normal manganese concentration was defined as 4.2 to 16.5 mcg/L. Main Results: A total of 27 subjects who were prescribed long-term parenteral nutrition were evaluated. Subjects had a median age of 54 years and range of 18 to 71 years. The majority of subjects (53%) were initially prescribed parenteral nutrition for enteric fistula or malabsorption issues while 27% of subjects were classified as have short gut. A total of 41 manganese concentrations were reported with a median value of 20.1 mcg/L and range of 9.1 to 49.9 mcg/L. The percentage of abnormally high manganese concentrations was 0% at 0-30 days, 63% at 30-90 days, 83% at 90-365 days, and 100% at >365 days of parenteral nutrition with manganese added through a multitrace element solution. In subjects who had received parenteral nutrition for at least 90 days without manganese, abnormal manganese concentrations reported rate was 28%. The rate of abnormal manganese concentrations was significant different between 0-30 days compared to 90-365 days (p = 0.015) and > 365 days (p =0.09) of multi-trace element added to parenteral nutrition. The median number of days between the initial day of parenteral nutition and day managanese concentration checked was 131 days and ranged from 0 to 849 days. Conclusion: The majority of commercially available trace element solutions contain approximately 500% per mL of the recommended daily supplementation amount. In 27 subjects who received long-term parenteral nutrition, the risk of hypermanganesemia was significantly associated with durations of parenteral nutrition that contained multi-trace element solutions for more than 90 days.