Manganese is an essential micronutrient found throughout the body, with the highest levels found in the liver. It accumulates in tissues high in mitochondria and is a cofactor in enzymes such as hexokinase, superoxide dismutase and xanthine oxidase. Manganese is associated with bone and tissue formation, carbohydrate metabolism, reproductive processes and lipid metabolism. Manganese is absorbed through the gastrointestinal tract with absorption being similar to iron absorption. Manganese is mainly excreted in bile with only a small amount excreted in urine. The human requirement for manganese is very low and even during prolonged TPN no clear evidence of deficiency has been documented. However because of the potential importance of manganese, additives containing it have been included in TPN regimens.
The concentration of whole blood manganese is about 10 times higher than in serum therefore the manganese from contamination is proportionately less significant, eliminating some sampling precautions. Whole blood manganese may better reflect manganese stores in tissue therefore it is recommended to use whole blood samples for assessment of manganese status and long term occupational exposure. Manganese is used in iron, steel and battery production industries. Occupational exposure to manganese is through the lungs via inhalation during mining of manganese ores and welding of mild steel (used as a toughening agent). Permanganate compounds are used in glass and ceramics industries and are also used as powerful oxidising agents.
Toxic effects
Exposure to high levels of manganese can cause non-specific symptoms and signs of neurological deterioration including irritability, apathy asthenia, headaches, lethargy and weakness in the extremities and in a few cases can lead to Parkinson's disease. These symptoms are believed to arise due to excess manganese deposition in the basal ganglia which can be seen as hyper-intense areas on MRI of the brain.
Manganese toxicity has also been documented in patients on long term TPN who are particularly at risk if there is liver dysfunction. Increased whole blood manganese has also been reported in liver disease, rheumatoid arthritis and iron deficiency anaemia. Neurological effects exhibit Parkinson like symptoms, including behavioral and emotional disturbances, if diagnosed in the early stages these effects can be reversed. Some haematological changes may also be observed, such as greatly reduced white cell count (leucopoenia) and lymphocytosis, or an increase in haemoglobin count. However in some cases there may be no changes at all.
Lipids/Trace Metals
BMN
7 days
6400