Arsenic, 24 hour, urine
The toxicity of arsenic is due to 3 different mechanisms, 2 of them related to energy transfer. Arsenic covalently and avidly binds to dihydrolipoic acid, a necessary cofactor for pyruvate dehydrogenase. Absence of the cofactor inhibits the conversion of pyruvate to acetyl coenzyme A, the first step in gluconeogenesis. This results in loss of energy supply to anaerobic cells, the predominant mechanism of action of arsenic on neural cells that rely on anaerobic respiration for energy. Neuron cell destruction that occurs after long-term energy loss results in bilateral peripheral neuropathy.
Normally, humans consume 5 to 25 mcg of arsenic each day as part of their normal diet; therefore, normal urine arsenic output is <25 mcg/specimen. After a seafood meal (seafood contains a nontoxic, organic form of arsenic), the urine output of arsenic may increase to 300 mcg/specimen for 1 day, after which it will decline to <25 mcg/specimen.
Exposure to inorganic arsenic, the toxic form of arsenic, causes prolonged excretion of arsenic in the urine for many days.
Urine excretion rates >1,000 mcg/specimen indicate significant exposure. The highest level observed at Mayo Clinic was 450,000 mcg/specimen in a patient with severe symptoms of gastrointestinal distress, shallow breathing with classic “garlic breath,” intermittent seizure activity, cardiac arrhythmias, and later onset of peripheral neuropathy.
- Sample of urine
- We perform the test upon request