Mercury (Blood)

Does this test have other names?

Hg level

What is this test?

This test measures the amount of mercury in your blood.

Mercury is a heavy metal that can be toxic. There are three different forms of mercury and each type can produce different symptoms if taken internally through eating or breathing its vapors, or if absorbed through the skin. It happens naturally as a liquid at room temperature and as an odorless vapor.

You can be exposed to mercury from polluted air or water. You can also be exposed if you work in an industry that still uses mercury, from eating fish that are high in mercury, and from some complementary and alternative health remedies. 

Long-term exposure to mercury can cause kidney and brain damage in adults. Exposure to mercury during pregnancy can cause permanent damage to the developing fetus. Breastfeeding may also expose infants to mercury.

Children who are exposed to mercury can suffer damage to their kidneys, nervous system, and digestive system.

Mercury is also in silver amalgam dental fillings. Tiny amounts of mercury may be absorbed from these fillings, but this amount is not likely to cause health problems.

Why do I need this test?

You may need this test if your healthcare provider suspects that you have mercury poisoning. Symptoms include:

• Fever

• Chills

• Chest tightness

• Shortness of breath

Inhaling mercury can cause:

• Nausea

• Diarrhea

• Vomiting

• Burning sensation in your mouth

You may also need this test to monitor your safety if it's possible that you could be exposed to mercury at your work. 

You may also have this test if you are pregnant or breastfeeding and have been exposed to high levels of mercury.

What other tests might I have along with this test?

Your healthcare provider may also order tests of your urine or breastmilk to measure for mercury. He or she may also test hair from your scalp to measure mercury exposure.

What do my test results mean?

Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you. 

The results of this test are given in nanograms per milliliter (ng/mL). Having some mercury in your blood does not mean you will develop health problems.

Here is the breakdown on higher results:

• 5 ng/mL. This may mean you are being exposed to unhealthy levels of mercury at your work or in your diet.

• 30 to 40 ng/mL. This level usually causes some symptoms and some brain or kidney damage.

• Above 100 ng/mL. This is considered mercury poisoning.

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

What might affect my test results?

Certain Chinese herbal products or skin-lightening creams that contain mercury can cause your blood level to rise. Eating fish and shellfish that contain high levels of mercury can raise your mercury levels.

How do I get ready for this test?

You don't need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.