Mercury Blood Test

What are the forms of Mercury?

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Mercury belongs to the category of heavy metals. A heavy metal is a general term used for a group of naturally occurring elements with a higher weight and density than water. The various forms of mercury affect the circulation of mercury in the ecosystem, its build-up, exposure, biological effects and toxicity in your body. The three main forms of mercury include:

Elemental mercury

Elemental or metallic mercury is found in thermometers and dental fillings. Mercury vapours can be easily inhaled and reach the lungs, where they combine with a protein to exert their effect. The mercury absorbed in the body mainly goes to the kidneys and brain. 

Inorganic mercury

This type of mercury exists in mineral ores combined with other elements. Inorganic mercury may be released into the air when coal is burned to generate power and as a waste product in various industrial processes.

Inorganic mercury primarily enters the body through inhalation into the lungs, and to a lesser extent, it is also absorbed through the skin or gastrointestinal tract. However, unlike metallic mercury, inorganic mercury cannot penetrate the blood-brain barrier and typically accumulates in the kidneys, the target organ. It is primarily excreted through the urine and faeces. Inorganic mercury released into the environment enters the sea, rivers, or streams. In the water, bacteria and plankton convert it into metallic mercury.

Organic mercury

Bacteria convert the elemental or metallic mercury in water to methylmercury, which is ingested or absorbed by fish and enters the food chain. Methylmercury is easily absorbed into the gut and lungs and is excreted via faeces and urine. As both metallic and organic mercury easily cross the blood–brain barrier and placenta, they can be excreted in breast milk and transmitted to the foetus.

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How can you get exposed to Mercury? 

Common sources of mercury exposure include:

• Large fish species:  The consumption of increased amounts of fish can increase the amount of mercury in your body.
• Fluorescent lamps, low-energy light bulbs and batteries: When the lamps and bulbs get damaged, there is a chance of inhaling mercury vapour and absorbing mercury through skin contact.
• Mercury thermometers:  Broken mercury thermometers can pose a mild to moderate risk if you inhale mercury vapour and absorb mercury through skin contact.
• Dental fillings: When amalgam fillings that contain mercury are replaced or removed from teeth, the risk of mercury exposure from inhaling mercury vapour and swallowing amalgam fragments increases.

When is the Mercury Blood test done?

Your doctor will recommend doing a blood test for mercury levels when there is a suspicion of mercury toxicity. A mercury lab test is done if:

• An acute mercury exposure has taken place between 3-20 days, with severe symptoms of mercury poisoning. This warrants emergency treatment
• You have a history of occupational exposure on a chronic basis
• Your symptoms mimic signs of mercury toxicity

What are the symptoms of Mercury exposure?

In the nineteenth century, many workers in European hat manufacturing factories were exposed to mercury. Similar occupational exposure was found in the thermometer manufacturing, fluorescent lamp manufacturing, and waste reprocessing industries from the 1980s to the early 2000s in Korea.

Furthermore, the outbreak of Minamata disease in Japan in 1956 highlighted the global health risks associated with mercury. In the incident, a chemical compound called acetaldehyde resulted in the production of methylmercury as a by-product in a fertiliser factory, which was released to the nearby shore. Over time, the marine ecosystem, involving fish and shellfish, became polluted with methylmercury. Approximately 5,000 residents who consumed seafood from the area either died or were injured. Later, other countries also reported cases of mercury exposure. 

Another condition that became popular among people born before 1950 and exposed to baby products containing mercury was Pink disease. In this condition, the feet, hands and the tip of the nose of the patients became bright pink. This was accompanied by diarrhoea and lethargy. Pink disease is now rare, but adults who had pink disease are more sensitive to mercury and may have several other health complaints.

Health effects from mercury exposure vary according to several factors, including how much mercury you were exposed to, the type of mercury, how you were exposed, how long the exposure was, and your age.

Symptoms of poisoning from elemental mercury

This kind of poisoning can happen from a broken mercury thermometer or other mercury-containing device spills. Mercury poisoning is often caused by inhaling mercury vapour, particularly in poorly ventilated places. Symptoms include:

• Neurological changes such as tremors, impaired sensations, headaches
• Physical changes such as muscle weakness and twitching
• Emotional changes such as mood swings, irritability, nervousness, sleep issues
• Damage to kidneys and lungs leading to urinary and breathing problems
• Death

Symptoms of organic (methylmercury) poisoning 

Methylmercury accumulates in tissues at a level that does not pose a risk to human health. Accumulation of an increased amount of methylmercury particularly affects your nervous symptom.
Methylmercury poisoning can cause disturbances in:

• Peripheral vision
• Sensation, especially on the hands, feet and mouth
• Speech and hearing
• Muscle strength, coordination and walking

Symptoms of poisoning from inorganic mercury

This type of poisoning is commonly associated with industrial exposure. Symptoms of inorganic mercury poisoning include:

• Skin conditions, including rashes and dermatitis
• Breathing problems
• Emotional changes, memory problems
• Reduction in muscle strength

How do you prepare for your Mercury lab test?

No special preparations are required for a mercury lab test.

A mercury lab test may be ordered in conjunction with a basic or comprehensive metabolic panel, which measures various substances in your blood. In this case, you may be required to fast for 8-12 hours before your blood draw; however, not always in case of emergency. It is recommended to stay hydrated by consuming an adequate amount of water when fasting. Your doctor will let you know if you need to follow any special instructions.

How is a Mercury lab test done?

The general steps of a blood test involve the following:

• A medical laboratory technician will check your arms for a vein that can be reached comfortably. This is usually in the inner part of your arm, on the other side of your elbow
• Upon location of the vein, they would clean and disinfect the area
• They would then insert a small needle into your vein to draw a blood sample, which might feel like a slight pinch
• After they insert the needle, a small amount of blood will collect in a test tube
•  They will remove the needle and press the bleeding site with a cotton ball or gauze to stop the bleeding
• A bandage will be applied to the site, and the collection of the sample will be done
• After a healthcare provider has collected your blood sample, they’ll send it to a laboratory for testing. Once the test results are back, your doctor will share the results with you

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Interpretation of test results

Mercury blood levels above 30nmol/L are considered positive. Any values below this level remain undetectable. Individuals with occupational exposure may have higher blood mercury levels.

Your doctor may recommend additional tests if you exhibit signs of mercury poisoning or have a history of exposure. Additional tests may include a complete blood count, comprehensive metabolic profile, chest X-ray, urinalysis, and electrocardiogram.

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How is Mercury poisoning treated?

Your history determines whether you have been exposed to mercury acutely or chronically, and the source of your mercury poisoning. In cases of acute exposure, your emergency room doctor will immediately decontaminate or remove the dangerous substance from your skin and clothing to avoid further exposure. Your symptoms will be managed promptly and tailored to the type of mercury exposure you have.

Treatment focuses on removing mercury from your body and providing you with support for your symptoms. Management strategies include:

• Chelation therapy for removing metals from your body via intravenous fluid
• Oxygen through a face mask
• Medicines to support symptoms
• Dialysis to remove toxins from your body
• Surgery to remove mercury

Damage from mercury can create long-term symptoms that require ongoing treatment even after initial treatment. Take care to address the long-lasting symptoms that might follow afterwards.

How can you reduce the exposure to Mercury?

Several precautions can be taken to minimise your exposure to mercury, as well as reduce the amount of mercury in your environment.

Mercury from fish

Fish such as shark, king mackerel, tuna, pike, walleye, and swordfish accumulate high levels of mercury and should be avoided. Fish oil products and supplements are not a significant source of dietary mercury and do not need to be restricted in your intake due to mercury content.

Most people can still eat fish with higher mercury levels. However, Food Standards Australia and New Zealand (FSANZ) recommend that they should be eaten less often. The FSANZ website guides on the portion size and number of portions of different types of fish that can be safely consumed in Australia.

Fluorescent lamps and low-energy light bulbs

A broken bulb or lamp would release mercury vapour, hence care needs to be taken around broken bulbs. New standards were introduced for low-energy bulbs in Australia in 2010.

Thermometers and other devices

With a broken mercury thermometer,  there is a chance of mercury exposure through inhaling mercury vapour and absorbing mercury through skin contact. Some other devices that can contain more than two tablespoons of mercury include thermostats and some medical equipment, such as a sphygmomanometer. 

Dental fillings                                                                                                                                  

Mercury vapour is released when old metal fillings are removed or replaced. Dentists take precautions when removing these old amalgam fillings and place a protective sheet over your mouth during the dental procedure. This traps any amalgam fragments, preventing them from being swallowed. Additionally, a high-pressure suction unit helps remove most of the solid amalgam and any mercury vapour.

New amalgam fillings should not be done, and existing amalgam fillings should not be removed or replaced in the following sensitive groups:

• Pregnant women: There is a risk of mercury crossing the placenta and entering the bloodstream of the unborn baby
• Women who are breastfeeding: Mercury may be passed to the baby through breastmilk, although the amount transferred is very low
• Children: The brain and nervous system are still growing and developing, together with teeth that are sensitive to the effects of  environmental toxins such as mercury
• People with kidney disease: High levels of mercury exposure can affect the kidneys

When Should I Get This Test?

You might wonder whether you need a mercury blood test if you don’t work in a lab or haven’t broken a thermometer at home. In reality, there are several situations when checking your mercury levels makes sense, even if you feel fine.

1. After a Known Exposure
• You’ve had a spill or accident with mercury-containing devices (thermometers, fluorescent lamps, batteries).
• You’ve handled or cleaned up broken bulbs, dental amalgam, or industrial wastes without proper protection.

2. Occupational or Environmental Risk
• You work in dentistry, manufacturing, mining, or laboratories where mercury is used or produced.
• You live near industries or waste sites known to release mercury into the air or water.
• You regularly consume well water from private wells in areas with natural mercury deposits.

3. High Fish Consumption
• You eat large, long-lived fish—such as shark, swordfish, king mackerel, or tuna—several times a week.
• You’re pregnant or breastfeeding and concerned about methylmercury crossing the placenta or into breast milk.

4. Unexplained Symptoms
• You notice tremors, memory issues, mood changes, or unusual fatigue without another clear cause.
• You have persistent digestive, respiratory, or kidney complaints that could signal low-level chronic exposure.

5. Routine Monitoring
• You’ve already had one elevated test: periodic follow-up (every 3–6 months) helps track trends.
• You’re in a high-risk group—children, older adults, or those with kidney disease—and want peace of mind.

Because blood mercury reflects recent exposure, testing within days of a suspected event is critical. For ongoing risks, a regular testing schedule can catch creeping increases before they lead to lasting damage. If any of these apply to you, talk to your doctor about adding a mercury blood test to your next check-up.

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Sources:

1. Fisher RM, Gupta V. Heavy Metals. [Updated 2024 Feb 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557806/.

2. Ye BJ, Kim BG, Jeon MJ, et al. Evaluation of mercury exposure level, clinical diagnosis and treatment for mercury intoxication. Ann Occup Environ Med. 2016;28:5. doi:10.1186/s40557-015-0086-8.

3. Better Health Channel. Victoria State Government – Mercury exposure and poisoning.‍

https://www.betterhealth.vic.gov.au/health/healthyliving/mercury-exposure-and-https://www.betterhealth.vic.gov.au/health/healthyliving/mercury-exposure-and-poisoning

4. Safe Work Australia – Hazardous chemicals requiring health monitoring.

https://www.safeworkaustralia.gov.au/system/files/documents/1702/hazardous-chemicals-requiring-health-monitoring.pdf.

5. Food Standards Australia – Mercury in fish.

https://www.foodstandards.gov.au/consumer/chemicals/mercury.