Manganese
Manganese (chemical symbol Mn) is one of the essential trace elements. It has an important biological role in the synthetic pathway for mucopolysaccharides, and it also is a cofactor for several enzymes.
Chemistry
Basic chemistry
Manganese has the atomic number 25 with an atomic weight of 54.94. It is a transition metal.
Radiochemistry
Manganese-55 is the only stable isotope. There are a large number (almost 30) of unstable isotopes, with mass numbers ranging from 44 to 73 .
Diet, absorption, transport and storage
In the normal human diet, manganese is primarily found in legumes, nuts and pulses, with smaller concentrations in leafy vegetables, tea, chocolate and several fruits (e.g. pineapple) .
Biological function
Manganese has many important roles, including:
- formation and activation of enzymes, e.g. oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases
- metabolizing carbohydrates and lipids
- synthesis of proteins, vitamin B complex and vitamin C
- hematopoiesis
Deficiency
Manganese deficiency is not seen in humans .
Toxicity
Overexposure to manganese is typically due to occupational exposure or with environmental exposure to air and water pollution. Manganese toxicity, whether acute or chronic, is known as manganism and may lead to parkinsonism .
Manganese-containing fumes have also been implicated as a precipitant in metal fume fever, although this is contentious .
Radiological importance
Manganese shortens T2 relaxation time, therefore solutions that contain manganese, such as pineapple juice, are used as negative oral contrast agents in MRCP .
Manganese shortens T1 relaxation time, thus manganese-based intravenous contrast agents are being investigated as an alternative to gadolinium-based contrast for MRI .
Related pathology
