Manganese (Mn) is a trace element that is an essential cofactor for several enzymes, including superoxide dismutase and the gluconeogenic enzymes: pyruvate carboxylase and isocitrate dehydrogenase. The required daily intake of 1 to 6 mg is readily supplied by a normal diet of fruits and vegetables.

Most circulating Mn is bound to hemoglobin inside erythrocytes. Whole blood concentrations of Mn are 10 times higher than plasma. Mn passes from erythrocytes to the tissues. Half-life of Mn in the body is about 40 days, with elimination primarily through the feces. Only small amounts are excreted in the urine.

Environmental exposure occurs from inhalation and ingestion of manganese-containing dust and fumes that are produced during refinement. Manganese alloys are used in the manufacturing of batteries, welding rods, and high-temperature refractory materials. Over exposure to manganese can be toxic, especially to the liver and central nervous system. Acute exposure to Mn fumes causes fever, dry mouth, and muscle pain. Chronic exposure causes CNS symptoms such as rigidity, depression and generalized parkinsonian features.

Elevated levels of whole blood Mn have also been reported in patients with cirrhosis and those with Behcet disease. Small studies have reported elevated levels in infants and adults receiving total parenteral nutrition.

Measurement of Mn in whole blood is the preferred method of analysis. Mn is analyzed using Dynamic Reaction Cell-Inductively Coupled Plasma-Mass Spectrometry. Reference range is 4.7-18.3 ng/mL. Values between 1 and 2 times the upper limit of normal may be due to differences in hematocrit and normal biological variation and should be interpreted with caution. Values greater than twice the upper limit of normal correlate with toxicity. Serial monitoring should not be ordered more frequently than every 40 days.

Specimen requirement is a royal blue-top (EDTA) Vacutainer plastic trace element blood collection tube. Failure to use metal-free collection procedures and contamination of the collection site may cause falsely increased results.

Choi Y, Park J, Park N, et al: Whole blood and red blood cell manganese reflected signal intensities of T1-weighted magnetic resonance images better than plasma manganese in liver cirrhotics. J Occup Health 2005;47:68-73

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