Two things caught our attention. First: Mechanical low back pain and the associated discogenic radiculopathy would be unilateral, manifesting with asymmetric paresthesias and pain. Our patient had weakness in gait and pain and burning in both of his legs. Second: Our patient described decreased sleep and feeling anxious, with symptoms of forgetfulness, confusion, and agitation. These factors prompted us to look beyond the normal differential and consider a potential toxicity. A heavy metal screen was ordered, and the results were positive for arsenic toxicity.
DISCUSSION
Arsenic toxicity is a global health problem that affects millions of people.1,2 Arsenic has been used for centuries in depilatories, cosmetics, poisons, and therapeutic agents. Today it is used as a treatment for leukemia and in several ayurvedic and homeopathic remedies.3-7 It is a common earth element found in ground water and a waste product from mining and the manufacturing of glass, computer chips, wood preservatives, and various pesticides.2,3,7,8
A great masquerader. Once in the body, arsenic can cause many serious ailments ranging from urinary tract, liver, and skin cancers to various peripheral and central nervous system disorders.2 Arsenic can cause symmetrical peripheral neuropathy characterized by sensory nerves being more sensitive than motor nerves.2,3,5,6 Clinically, it causes numbness and paresthesias of the distal extremities, with the lower extremities more severely affected.3,6 Symptoms can develop within 2 hours to 2 years of exposure, with vomiting, diarrhea, or both preceding the onset of the neuropathy.2,3,5,6 Arsenic is linked to forgetfulness, confusion, visual distortion, sleep disturbances, decreased concentration, disorientation, severe agitation, paranoid ideation, emotional lability, and decreases in locomotor activity.3,5,6
Testing and treatment. Arsenic levels in the body are measured by blood and urine testing. Blood arsenic levels are typically detectable immediately after exposure and with continued exposure, but quickly normalize as the metal integrates into the nonvascular tissues. Urine arsenic levels can be detected for weeks. Normal levels for arsenic in both urine and blood are ≤ 12 µg/L.3 Anything greater than 12 µg/L is considered high; critically high values are those above 50 µg/L.3,5 Our patient’s blood arsenic level was 13 µg/L.
Treatment involves removing the source of the arsenic. Chelation therapy should be pursued when urine arsenic levels are greater than 50 µg/L or when removing the source of the arsenic fails to reduce arsenic levels. Chelation therapy should be continued until urine arsenic levels are below 20 µg/L.5,6
Continue to: After discussing potential sources of exposure