Overview of Mercury Tests

Mercury can enter the body through ingestion, inhalation, or dermal exposure, and it can accumulate over time, leading to toxicity. The two most common forms of mercury that are tested for are elemental mercury (found in thermometers, fluorescent lights) and methylmercury (found in fish and seafood).

Risk Assessment

• Occupational exposure: People working in industries like mining, manufacturing of thermometers or batteries, or in dental practices (due to mercury used in amalgams) are at higher risk.
• Environmental exposure: Consumption of contaminated fish, especially large predatory fish like tuna or swordfish, can contribute to methylmercury exposure.
• Accidental exposure: Some products, such as thermometers, can release mercury if broken.

Normal Range

The "normal" range can vary based on the type of mercury test and the laboratory used, but generally:

• Blood Mercury Level: Less than 5 ng/mL is considered normal, although a value above this may indicate recent exposure.
• Urine Mercury Level: Typically, a concentration below 10 μg/L is considered normal, with higher values suggesting exposure.

Interpretation of Results

• Blood Test: Mercury levels in blood reflect recent exposure. A high level indicates recent exposure, and the body may still be in the process of eliminating it. Chronic exposure may show a lower blood mercury concentration but higher levels in urine or tissues.
• Urine Test: Urinary mercury levels are typically higher in individuals exposed to inorganic mercury (e.g., elemental mercury). It’s often used to assess ongoing exposure or elimination of mercury from the body.

Signs of Mercury Toxicity:

• Neurological symptoms: tremors, memory problems, irritability, insomnia
• Renal (kidney) symptoms: protein in urine, kidney dysfunction
• Gastrointestinal symptoms: abdominal pain, nausea, diarrhea
• Cardiovascular symptoms: high blood pressure, arrhythmias.

Sample Types

• Blood Sample: A blood sample is drawn from a vein (venipuncture) to measure the level of mercury in circulation.
• Urine Sample: A urine sample is collected, often through a standard midstream collection, to assess the mercury content in the urine.