Mercury
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- Also Known As:
- Hg (chemical symbol)
- Formal Name:
- Mercury
- Urine and Blood

This page was fact checked by our expert Medical Review Board for accuracy and objectivity. Read more about our editorial policy and review process.
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At a Glance
Why Get Tested?
To detect excessive exposure to mercury
When To Get Tested?
When you have signs and symptoms of mercury poisoning or have been exposed to mercury; to monitor occupational exposure to mercury
Sample Required?
A blood sample drawn from a vein in your arm and/or a random or 24-hour urine sample may be collected. Rarely, another sample such as hair, breast milk, or nails may be tested.
Test Preparation Needed?
None needed; however, consult with your health care provider or laboratory about urine collection to avoid sample contamination.
You may be able to find your test results on your laboratory’s website or patient portal. However, you are currently at Testing.com. You may have been directed here by your lab’s website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab’s website or portal, or contact your healthcare practitioner in order to obtain your test results.
Testing.com is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.
The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.
If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.
Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called “normal” values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.
While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are “within normal limits.”
For more information, please read the article Reference Ranges and What They Mean.
What is being tested?
Mercury is an element that can be toxic in various forms, which are tested in different samples:
- Metallic or elemental mercury is a liquid often used in dental fillings, some thermometers, and batteries. Urine samples are typically tested to detect this form of mercury.
- Inorganic mercury salts, which are produced by the reaction of non-carbon based compounds with mercury, are normally in a form of powder or crystal and sometimes used in topical preparations such as skin-lightening or antiseptic creams. Urine samples are usually used to detect this form of mercury.
- Methyl mercury and other organic mercury compounds are products of reactions between mercury and carbon-based organic compounds. Bacteria with elevated levels of methyl mercury are often found in large, older, predator fish such as sharks and king mackerel. People who eat these fish may be exposed to this form of mercury. Blood is primarily used to identify a high level of methyl mercury.
Mercury is found in small quantities throughout the environment. It is released by the breakdown of minerals in rocks and soils and as a byproduct of fossil fuel combustion and waste incineration. It is inhaled with the air that we breathe, absorbed through the skin, and ingested with food. Mercury is also used in some mirror coatings, pharmaceuticals, and agricultural chemicals. Energy efficient compact fluorescent light (CFL) bulbs contain small amounts of mercury, which is also used to make electrical equipment, wire, and switching devices.
The tiny amounts to which the vast majority of people are exposed do not generally cause health concerns. However, people may develop mercury-related symptoms or complications if they are exposed to dangerous concentrations of mercury, such as might be found at a hazardous waste site, or are exposed to mercury over long periods of time, especially if they work with heavy metals on the job.
Exposure to excessive amounts of mercury can be toxic. The amount of mercury absorbed by an individual and its effects on the person’s health depends on the type of mercury, its concentration, and the nature of exposure. According to the Agency for Toxic Substances and Disease Registry (ATSDR), very little metallic mercury (less than 0.01%) is absorbed by the body, even if it is swallowed. However, if the same mercury is inhaled as a vapor, about 80% is absorbed into the bloodstream.
About 95% of methyl mercury, which is the type found in fish and other seafood, is absorbed by the digestive tract. The most common source of human exposure to methyl mercury is eating contaminated seafood. Fish that come from contaminated waters and large predator fish that have eaten smaller fish may have significantly increased levels of methyl mercury. It is important to know the source of the fish that you consume and to limit the quantity of large predator fish eaten.
Once mercury is absorbed, the body may deposit it in a variety of body organs, including the kidneys and brain. The body will slowly rid itself of mercury through the urine and stool, but if an excessive amount accumulates, it can permanently damage the kidneys, nervous system, and brain.
Pregnant women with elevated levels of mercury can pass it on to their unborn baby, affecting development of the baby’s brain, kidneys, and nerves especially. Mercury can also be passed from mother to baby through breast milk during nursing.
Common Questions
View Sources
Sources Used in Current Review
Olson, D. (2017 August 13, Updated). Mercury Toxicity. Medscape Neurology. Available online at https://emedicine.medscape.com/article/1175560-overview. Accessed on 10/06/18.
(© 1995–2018). Mercury, Blood. Mayo Clinic Mayo Medical Laboratories. Available online at https://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/8618. Accessed on 10/06/18.
(2018 February 16, Updated). Health Effects of Exposures to Mercury. US Environmental Protection Agency. Available online at https://www.epa.gov/mercury/health-effects-exposures-mercury. Accessed on 10/06/18.
(2018 September 10, Updated). About Mercury. Agency for Toxic Substances and Disease Registry, Don’t Mess with Mercury. Available online at https://www.atsdr.cdc.gov/dontmesswithmercury/about_mercury.html. Accessed on 10/06/18.
Heller, J. et. al. (2017 September 23, Updated). Mercury poisoning. MedlinePlus Medical Encyclopedia. Available online at https://medlineplus.gov/ency/article/002476.htm. Accessed on 10/06/18.
Adal, A. and Wiener, S. (2018 August 24, Updated). Heavy Metal Toxicity. Medscape Emergency Medicine. Available online at https://emedicine.medscape.com/article/814960-overview. Accessed on 10/06/18.
Brooks, M. (2018 May 24). AHA Advisory Recommends Fish Twice Weekly for CV Health. Medscape Medical News. Available online at https://www.medscape.com/viewarticle/897212. Accessed on 10/06/18.
(2017 November 1, Updated). Methylmercury in Fish. MotherToBaby. Available online at https://mothertobaby.org/fact-sheets/methylmercury-pregnancy/. Accessed on 10/06/18.
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(2004 August 02, Updated). Public Health Statement for Mercury. Agency for Toxic Substances and Disease Registry (ATSDR) [On-line information]. Available online at http://www.atsdr.cdc.gov/toxprofiles/phs46.html through http://www.atsdr.cdc.gov.
Severson, T. (2003 May 12, Updated). Mercury. MedlinePlus Health Information, Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/002476.htm.
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(© 2004). Mercury. ARUP’s Guide to Clinical Laboratory Testing [On-line information]. Available online at http://www.aruplab.com/guides/clt/tests/clt_al12.jsp#2124716.
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Cain, A. (2004 August 04, Updated). Mercury: A Brief for the Binational Strategy Implementation Workgroup, Frequently Asked Questions about Mercury Fever Thermometers. Great Lakes Binational Strategy Implementation Workshop [On-line information]. Available online at http://www.epa.gov/glnpo/bnsdocs/hg/thermfaq.html.
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(2007 July 24). Sushi lovers cautioned over mercury levels in tuna. MedlinePlus from Reuters Health Information [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/news/fullstory_52573.html. Accessed on 8/12/07.
Preidt, R. (2007 June 14). Antiques Can Pose a Mercury Danger Today. MedlinePlus from HealthDay [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/news/fullstory_50928.html. Accessed on 8/12/07.
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(Updated September 3, 2010) Department of Health and Human Services, The Center for the Evaluation of Risks to Human Reproduction. Mercury. Available online at http://cerhr.niehs.nih.gov/common/mercury.html. Accessed May 2011.
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