Manganese toxicity
Contents
Background
- An essential element in the diet
- Used in various enzymatic processes
- Mn2+ can take the place of Mg2+, Ca2+, and Fe2+ in various proteins and enzymes, and has been seen to replace Fe2+ in Hgb
- Low enteral absorption
- Cleared by the liver and excreted in the bile
- Typical routes of exposure
- Inhalation of dusts/fumes
- Seen in industrial areas as manganese is used to make steel
- Parenteral nutrition (TPN)
- IV Methcathinone
- Inhalation of dusts/fumes
- Readily crosses the blood brain barrier and can be seen concentrated in the basal ganglia, particularly the globus pallidus
Clinical Features
- Toxicity typically presents as cognitive issues
- Neuropsychiatric
- Acute
- “Manganese madness”
- Visual hallucinations
- Behavioral changes
- Anxiety
- Impotence
- Late manifestations
- Tremor
- Impaired speech
- Loss of facial expressions
- Gait disturbances
- Low volume speech
- Can mimic Parkinson’s disease
- Acute
- Pulmonary
- Acute / Metal fume fever
- Chronic
- Persistent dry cough
- Bronchitis
- Chemical pneumonitis
- GI
- Anorexia
- Musculoskeletal
- Arthralgia
- Muscle rigidity
- Constitutional
Differential Diagnosis
Heavy metal toxicity
- Aluminum toxicity
- Antimony toxicity
- Arsenic toxicity
- Barium toxicity
- Bismuth toxicity
- Cadmium toxicity
- Chromium toxicity
- Cobalt toxicity
- Copper toxicity
- Gold toxicity
- Iron toxicity
- Lead toxicity
- Lithium toxicity
- Manganese toxicity
- Mercury toxicity
- Nickel toxicity
- Phosphorus toxicity
- Platinum toxicity
- Selenium toxicity
- Silver toxicity
- Thallium toxicity
- Tin toxicity
- Zinc toxicity
Evaluation
- Lab
- Whole blood 4-15 μg/L (73-273 nmol/L)
- Serum 0.9-2.9 μg/L (16-52 nmol/L)
- Urine (24h) <10 μg/L (182 nmol/L)
- No definite toxic level
- Elevated levels are typically seen in acute toxicity, as manganese is quickly cleared from the blood
- MRI
- Will show abnormal T1- weighted signal hyperintensity in the basal ganglia, particularly in the globus pallidus, with normal T2-weighted images
Management
- Supportive care
- Remove source of exposure
- Chelation therapy with CaNa2EDTA or DTPA
- Can improve urinary excretion of manganese without affecting the neurologic manifestations
Disposition
- Will depend on severity, most cases are likely seen in patients receiving TPN, and will likely need changes to their TPN orders and a consultation from nutrition
- Consult Toxicology or poison control
References
Soghoian, S. Manganese. In: Goldfrank's Toxicologic Emergencies. 9th Ed. New York: McGraw-Hill; 2011: 1294-1298