Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

ASU
8644
0-24 mcg/L
Reference values apply to all ages.
Clinical References: Caldwell KL, Jones RL, Verdon CP, et al: Levels of urinary total and speciated
arsenic in the US population: National Health and Nutrition Examination Survey 2003-2004. J Expo Sci
Environ Epidemiol 2009;19:59-68
Arsenic, 24 Hour, Urine
Clinical Information: Arsenic is perhaps the best known of the metal toxins, having gained notoriety
from its extensive use by Renaissance nobility as an antisyphilitic agent and, paradoxically, as an antidote
against acute arsenic poisoning. Even today, arsenic is still 1 of the more common toxicants found in
insecticides, and leaching from bedrock to contaminate groundwater. 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. Arsenic also competes with phosphate for binding to adenosine
triphosphate during its synthesis by mitochondria via oxidative phosphorylation, causing formation of the
lower energy adenosine diphosphate monoarsine. This results in loss of energy supply to aerobic cells.
Cardiac cells are particularly sensitive to this form of energy loss; fatigue due to poor cardiac output is a
common symptom of arsenic exposure. Arsenic furthermore binds avidly with any hydrated sulfhydryl
group on protein, distorting the 3-dimensional configuration of that protein, causing it to lose activity.
Interaction of arsenic with epithelial cell protein at the sites of highest physiologic concentration, the
small intestine and proximal tubule of the kidney, results in cellular degeneration. Epithelial cell erosion
in the gastrointestinal tract and proximal tubule are characteristic of arsenic toxicity. Arsenic is also a
know carcinogen, but the mechanism of this effect is not definitively known. A wide range of signs and
symptoms may be seen in acute arsenic poisoning including headache, nausea, vomiting, diarrhea,
abdominal pain, hypotension, fever, hemolysis, seizures, and mental status changes. Symptoms of chronic
poisoning, also called arseniasis, are mostly insidious and nonspecific. The gastrointestinal tract, skin, and
central nervous system are usually involved. Nausea, epigastric pain, colic abdominal pain, diarrhea, and
paresthesias of the hands and feet can occur. Arsenic exists in a number of different forms; organic forms
are nontoxic, inorganic forms are toxic. See ASFR/80375 Arsenic Fractionation, 24 Hour, Urine for
details about arsenic forms. Because arsenic is excreted predominantly by glomerular filtration, analysis
for arsenic in urine is the best screening test to detect arsenic exposure.
Useful For: Preferred screening test for detection of arsenic exposure
Interpretation: Normally, humans consume 5 to 25 mcg of arsenic each day as part of their normal
diet; therefore, normal urine arsenic output is