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Mercury

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Also known as: Hg (chemical symbol)
Formal name: Mercury, Urine and Blood

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 urine collection

Test Preparation Needed?

None

The Test Sample

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 chronically 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 his or her 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 as consumption of 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.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm or a random or 24-hour urine sample may be collected. Rarely, another sample such as hair, breast milk, or nails may be tested.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed. Consult your healthcare provider or laboratory about urine collection to avoid sample contamination.

The Test

Common Questions

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Article Sources

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Sources Used in Current Review

Jamshid Eshraghi, PhD. Director, Chemistry Division. Massachusetts State Public Health Laboratory.

Mercury, Blood. Mayo Clinic. Available online at http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/8618 through http://www.mayomedicallaboratories.com. Accessed September 26, 2014.

David Olson. Mercury Toxicity Clinical Presentation. Medscape. Available online at http://emedicine.medscape.com/article/1175560-clinical through http://emedicine.medscape.com. Last Updated March 8, 2013. Accessed September 26, 2014.

Vaccine Education Center: Vaccines and Thimerosal. Children's Hospital of Philadelphia. Available online at http://www.chop.edu/service/vaccine-education-center/vaccine-safety/vaccine-ingredients/thimerosal.html through http://www.chop.edu. Reviewed March 2014. Accessed September 26, 2014.

About Dental Amalgam Fillings. U.S. Food and Drug Administration. Available online at http://www.fda.gov/medicaldevices/productsandmedicalprocedures/dentalproducts/dentalamalgam/ucm171094.htm through http://www.fda.gov. Last updated June 6, 2014. Accessed September 26, 2014.

Mercury. Tox Town. National Institutes of Health. Available online at http://toxtown.nlm.nih.gov/text_version/chemicals.php?id=17 through http://toxtown.nlm.nih.gov. Accessed September 26, 2014.

Reducing Your Exposure to Mercury. Oregon Environmental Council. Available online at http://www.oeconline.org/our-work/healthier-lives/pollutioninpeople/solutions/mercury through http://www.oeconline.org. Accessed September 26, 2014.

(February 14, 2013) Centers for Disease Control and Prevention. Emergency Preparedness and Response, Mercury. Available online at http://emergency.cdc.gov/agent/mercury/ through http://emergency.cdc.gov. Accessed October 2014.

Sources Used in Previous Reviews

Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.

(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.

Severson, T. (2003 April 30, Updated). Mercuric chloride. MedlinePlus Health Information, Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/002474.htm.

(© 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 through http://www.aruplab.com.

Baratz, R. (2003 June 26). Dubious Mercury Testing. Quackwatch [On-line information]. Available online at http://www.quackwatch.org/01QuackeryRelatedTopics/Tests/mercurytests.html through http://www.quackwatch.org.

Wellbery, C. (2004 April 15). Can Vaccines Containing Thimerosal Cause Autism? American Family Physician, Tips from Other Journals [from Hviid A, et al. Association between thimerosal-containing vaccine and autism. JAMA October 1, 2003;290:1763-6.] [On-line journal]. Available online at http://www.aafp.org/afp/20040415/tips/7.html through http://www.aafp.org.

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 through http://www.epa.gov.

(2004 May) NIAID Research on Thimerosal. NIAID Fact Sheet [On-line information]. Available online at http://www.niaid.nih.gov/factsheets/thimerosal.htm through http://www.niaid.nih.gov.

(2002 December 31). Consumer Update: Dental Amalgams. U.S. FDA, CDRH Consumer Information [On-line information]. Available online at http://www.fda.gov/cdrh/consumer/amalgams.html through http://www.fda.gov.

(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 through http://www.nlm.nih.gov. 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 through http://www.nlm.nih.gov. Accessed on 8/12/07.

(2007 August 7). Mercury, Health Effects. Environmental Protection Agency [On-line information]. Available online at http://www.epa.gov/mercury/effects.htm through http://www.epa.gov. Accessed on 8/12/07.

Perez, E. (2006 December 6, Updated). Mercury. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/002476.htm. Accessed on 8/12/07.

Perez, E. (2006 July 18 Updated). Methylmercury poisoning. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/001651.htm. Accessed on 8/12/07.

Xue, F. et. al. (2007 March 12). Maternal Fish Consumption, Mercury Levels, and Risk of Preterm Delivery. Medscape from Environ Health Perspect. 2007;115(1):42-47. [On-line information]. Available online at http://www.medscape.com/viewarticle/553133 through http://www.medscape.com. Accessed on 8/12/07.

Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry. AACC Press, Washington, DC. Pg 474.

Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. Pp 722-724.

Tietz Textbook of Clinical Chemistry and Molecular Diagnostics Burtis CA, Ashwood ER, Bruns DE, eds. 4th edition, St. Louis: Elsevier Saunders; 2006.

Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference, 8th Edition: Mosby, Inc., Saint Louis, MO.

Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. McPherson RA, Pincus MR, eds. Saunders Elsevier: 2007.

LaDuo, J. Occupational and Environmental Medicine, 2nd ed, 1997 Pp. 421-423.

(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 through http://cerhr.niehs.nih.gov. Accessed May 2011.

(Updated March 3, 2011) Agency for Toxic Substances and Disease Registry. Public Health Statement for Mercury. Available online at http://www.atsdr.cdc.gov/phs/phs.asp?id=112&tid=24 through http://www.atsdr.cdc.gov. Accessed May 2011.

(February 2009) Agency for Toxic Substance and Disease Registry. Evaluating for Mercury Exposure: Information for Health Care Providers. PDF available for download at http://www.atsdr.cdc.gov/mercury/docs/Physician_Hg_Flier.pdf through http://www.atsdr.cdc.gov. Accessed May 2011.

(Updated September 21, 2009) Olsen D. Mercury. Medscape article. Available online at http://emedicine.medscape.com/article/1175560-overview through http://emedicine.medscape.com. Accessed May 2011.

(Updated September 11, 2009) Diner B. Mercury Toxicity in Emergency Medicine. eMedicine article. Available online at http://emedicine.medscape.com/article/1175560-overview through http://emedicine.medscape.com. Accessed May 2011.

(Updated June 30, 2010) Tan D. Pediatric Mercury Toxicity. eMedicine article. Available online at http://emedicine.medscape.com/article/1009691-overview through http://emedicine.medscape.com. Accessed May 2011.

(February 2, 2009) MedlinePlus Medical Encyclopedia. Mercury. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/002476.htm. Accessed May 2011.

Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER, Bruns DE, eds. St. Louis: Elsevier Saunders; 2006, Pp1381-1382.

(December 9, 2009) National Institute of Allergy and Infectious Diseases. Vaccines, Thimerosal in vaccines. Available online at http://www.niaid.nih.gov/topics/vaccines/research/Pages/vaccines.aspx through http://www.niaid.nih.gov. Accessed May 2011.

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