Mn

Manganese

Vitamins & Minerals

What is Manganese?

Manganese is an essential trace mineral required for the activity of several important metalloenzymes, including manganese superoxide dismutase (MnSOD, the primary mitochondrial antioxidant enzyme), arginase (urea cycle), pyruvate carboxylase (gluconeogenesis), and glycosyltransferases (proteoglycan and glycoprotein synthesis critical for cartilage and bone formation). Manganese also activates numerous other enzymes as a nonspecific cofactor, though magnesium can often substitute in these roles.

Dietary sources of manganese include whole grains, nuts, legumes, tea, leafy vegetables, and pineapple. Absorption occurs in the small intestine via DMT1 (the same transporter used by iron), and homeostasis is primarily maintained by hepatic regulation of biliary excretion rather than by controlling absorption. Whole blood manganese is the preferred clinical specimen, as serum levels are very low and less reliable. Occupational exposure (welding, mining, steel manufacturing) is the most common cause of manganese toxicity, which causes a characteristic parkinsonian syndrome known as manganism.

Why It Matters

Manganese plays a critical role as the cofactor for MnSOD, the primary antioxidant defense within mitochondria—without it, mitochondrial oxidative damage accumulates. Manganese is also essential for normal bone development and maintenance through its role in glycosyltransferases that synthesize proteoglycans in cartilage and bone matrix. While dietary deficiency is extremely rare in humans, manganese toxicity from occupational or environmental exposure is a well-documented cause of irreversible neurological damage that closely resembles Parkinson disease. The narrow therapeutic window of manganese (essential at low doses, toxic at higher levels) makes monitoring important in at-risk populations.

Normal Reference Ranges

GroupRangeUnit
Adults (whole blood)4.7–18.3µg/L
Adults (serum)0.4–0.85µg/L

Reference ranges may vary by laboratory. Always compare results to the ranges provided by your testing facility.

What High Mn Levels Mean

Common Causes

  • Occupational exposure (welding fumes, mining, steel/battery manufacturing)
  • Contaminated drinking water
  • Chronic liver disease (impaired biliary excretion)
  • Prolonged parenteral nutrition with manganese
  • Iron deficiency (increased intestinal absorption via shared transporters)
  • Neonates and infants (immature biliary excretion)

Possible Symptoms

  • Manganism: bradykinesia, rigidity, tremor (resembles Parkinson disease)
  • Psychiatric symptoms: irritability, aggression, hallucinations ("manganese madness")
  • Cognitive impairment and memory loss
  • Gait abnormalities (characteristic "cock walk")
  • Headaches and insomnia (early symptoms)
  • Hepatic dysfunction

What to do: Remove the source of exposure immediately—this is the most critical intervention. In occupational settings, ensure proper ventilation and respiratory protection. For parenteral nutrition, reduce or eliminate manganese supplementation and monitor levels. Chelation therapy with EDTA or para-aminosalicylic acid (PAS) has shown some benefit, but neurological damage from chronic exposure is often irreversible. Brain MRI typically shows T1-weighted hyperintensity in the globus pallidus, a hallmark finding. Levodopa is less effective for manganism than for Parkinson disease.

What Low Mn Levels Mean

Common Causes

  • Extremely restrictive diets (very rare cause of clinical deficiency)
  • Chronic malabsorption (theoretical)
  • Excessive iron or calcium supplementation (competitive inhibition)

Possible Symptoms

  • Impaired bone growth and skeletal abnormalities (observed in animals)
  • Dermatitis
  • Impaired glucose tolerance
  • Altered lipid metabolism
  • Impaired reproductive function (observed in animals)

What to do: Clinical manganese deficiency is exceptionally rare in free-living humans and has only been clearly documented in experimental settings. If suspected, ensure adequate dietary intake through whole grains, nuts, tea, and leafy vegetables. The adequate intake is 2.3 mg/day for men and 1.8 mg/day for women. Avoid excessive iron or calcium supplementation that could compete with manganese absorption. Most varied diets provide sufficient manganese.

When Is Mn Testing Recommended?

  • In workers with occupational exposure to manganese (welding, mining)
  • When parkinsonian symptoms occur in young individuals
  • In patients on long-term parenteral nutrition
  • When chronic liver disease may impair manganese excretion
  • In environmental exposure investigations
  • When unexplained neuropsychiatric symptoms are present in at-risk populations

Frequently Asked Questions

While manganism closely resembles Parkinson disease clinically, there are important differences. Manganism preferentially damages the globus pallidus (visible as T1 hyperintensity on MRI), while Parkinson disease primarily affects the substantia nigra. Manganism tends to cause a more symmetrical onset, a distinctive gait disturbance ("cock walk" with toe-walking), more prominent psychiatric symptoms early on, and less resting tremor than classic Parkinson disease. Importantly, manganism responds poorly to levodopa (the standard Parkinson treatment) because the damage is downstream of where dopamine is produced. Manganism also does not involve Lewy body pathology.
Yes, welders are one of the most studied occupational groups for manganese exposure. Welding fumes, particularly from mild steel and stainless steel welding, contain significant amounts of manganese compounds in respirable particle sizes. Inhaled manganese bypasses the liver's first-pass regulation and can enter the brain directly via the olfactory nerve. Studies have shown that even welders without overt manganism may have subtle neurological deficits on neuropsychological testing. OSHA and ACGIH have set occupational exposure limits, and proper ventilation, respiratory protection, and biomonitoring are recommended.
Manganese naturally occurs in groundwater, and concentrations above 0.1 mg/L can cause aesthetic issues (discoloration, metallic taste). The WHO health-based guideline value is 0.08 mg/L for drinking water. Epidemiological studies, particularly in children, have associated elevated manganese in drinking water with reduced IQ scores, impaired memory, and attention deficits. Children are especially vulnerable because they absorb more manganese than adults and have less developed biliary excretion. Some jurisdictions now monitor and regulate manganese in drinking water, particularly in areas with high natural levels.

Related Biomarkers

FeSerum IronFerritinFerritinCuCopperZnZincMgMagnesium

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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Reference ranges may vary between laboratories. Always consult your healthcare provider for interpretation of your specific test results.

Disclaimer: SymptomGPT is not a medical diagnosis tool and does not provide medical advice. Always consult a qualified healthcare professional. If you are experiencing a medical emergency, call 911 immediately.