Arsenic urine test

The ingested arsenic does not stay for more than 2 days in the bloodstream. Most of it distributes to various tissues and is finally eliminated in the urine. Thus, urine is the preferred sample for testing chronic arsenic exposure. Arsenic is eliminated in the urine within six days from the time of exposure.

Your doctor may order this test if you have the following symptoms of chronic arsenic exposure:

• Abdominal pain
• Diarrhoea
• Sore throat
• Increased risk of diabetes mellitus
• Skin conditions:
  • Hyperpigmentation as ‘raindrop appearance’, dark spots or diffuse darkening of the skin
  • Keratosis on the palms and soles as discrete nodules or uniform thickening
  • Skin cancers such as Bowen’s disease and basal cell carcinoma
  • White lines in the nails known as Mee’s lines
• Gastrointestinal symptoms:
  • Recurrent bouts of diarrhoea associated with vomiting
  • Hepatomegaly
• Cardiovascular symptoms:
  • Myocardial injury
  • Cardiomyopathy
  • Cardiac arrhythmia
  • Black foot disease, which causes gangrene in the foot, seen in some regions of Taiwan
  • Peripheral vascular disease
• Neurological symptoms:
  • Peripheral neuropathy similar to that seen in Guillain–Barré syndrome
  • Confusion
  • Changes in behaviour
  • Memory loss
  • Neutropenia
• Risks of developing cancers in the following different organs:
  • Lung
  • Kidney
  • Skin
  • Liver
  • Bladder

Do not consume seafood before this test as it will increase the amount of arsenic in your urine. If you have undergone any test that uses gadolinium-containing contrast medium, wait for at least 48 hours before sample collection as gadolinium may affect the test results.

Earlier, a 24-hour urine sample was collected for this test but now a spot urine sample collection - a single sample at any time of the day - is done.

You will be provided with a container for sample collection. As you collect the sample, make sure that it does not get contaminated with blood or faecal matter. A ‘clean catch method’, as follows, is used for spot urine collection to prevent contamination of the sample:

• Wash your hands and genital area before collecting the sample.
• While you are urinating, let some urine flow into the toilet first and stop the flow. 
• Then urinate carefully into a container till the marking on the container. 
• Finish urinating into the toilet.

Close the container and take it to the laboratory for testing or store it in the refrigerator till you submit it to the laboratory for testing.  

For infants, the sample collection is a little different. You will be provided with a bag with a sticky edge, which will fit over the genital area of the baby. The test is performed as follows:

• Clean the genital area of the infant with soap and water.
• Place the bag over the genitals of your infant.
• In case of boys, include the entire penis in the bag and for girls, position the bag over the labia.
• You can make the baby wear the diaper over the bag.
• Repeatedly check if the infant has urinated and once the bag is filled, remove it.
• Move the sample into the container and take it to the laboratory.

Normal results:

The normal values of arsenic in the urine are in the range of 0-34.9 mcg/L. This range includes a combination of inorganic arsenic and its methylated metabolites. Humans consume about 5-25 mcg arsenic on a daily basis. Consuming seafood will raise the levels of arsenic in the urine up to 300 mcg/L; however, the amount declines after a day.

Abnormal results:

Arsenic toxicity is diagnosed by correlating the test results with the signs and symptoms of arsenic toxicity. In the case of toxicity, the total urine arsenic content may exceed 1000 mcg/L. If total arsenic values in urine are in the range 35-2000mcg/L, they are fractionated for proportions of inorganic arsenic, methylated metabolites and organic arsenic to determine toxicity. The total arsenic concentration may be higher than the sum of organic, inorganic and methylated arsenic due to the presence of unidentified arsenic species.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.