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MANGANESE TOXICITY IN PATIENTS ON LONG-TERM HOME TOTAL PARENTERAL NUTRITION THERAPY
L Stevens, M Rashid1
Dalhousie Medical School, 1Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia
BACKGROUND: Manganese is an essential trace element routinely added to total parenteral nutrition (TPN) solutions. Manganese levels are not routinely measured in patients and manganese toxicity remains a possibility.
OBJECTIVES: To report manganese toxicity with hypermanganesemia and abnormal brain deposits in two patients receiving long-term home TPN therapy.
METHODS: Two males age 25 and 57 years with intestinal insufficiency were on daily home-TPN for several years. Both were receiving standard manganese supplementation in the trace element preparation Micro+®6 injection consisting of manganese, zinc, copper, chromium, selenium and iodine. The daily dose administered in the TPN was 1 ml of the injection providing 0.5 mg of manganese per day. The 25 year-old patient was admitted with central venous catheter infection and exhibited neuropsychiatric symptoms including depression and suicidal ideations. The other patient had no symptoms.
RESULTS: Plasma manganese level in the first case was elevated at 59.9 nmol/L (normal 5.5-18.2 nmol/L). Bilateral increased signal on T1 sequences were seen in the putamina, in the anterior thalami and in the cerebral peduncles symmetrically on magnetic resonance imaging (MRI). This was in keeping with manganese deposition in the brain. The plasma manganese level in the second case was also elevated at 42.0 nmol/L. On brain MRI bilateral increased T1 signal intensity was seen in the globus pallidus, suggestive of manganese deposition. Nine months after the removal of manganese from TPN formulations, manganese levels were normal in the first patient and near normal in the other. A repeat MRI of the first case was normal and he had no further neuropsychiatric symptoms.
CONCLUSIONS: Hypermanganesemia and neurotoxicity can occur in patients on long-term TPN therapy. Manganese requirements in TPN formulations should be assessed on an individual basis with careful monitoring of manganese levels in these patients.