From the Guidelines
Diagnosis of Heavy Metal Poisoning Heavy metal poisoning is typically diagnosed through a combination of clinical evaluation, laboratory tests, and medical history. The diagnosis is often made based on symptoms such as hematemesis, hypotension, melena, coma, headaches, behavioral changes, fever, diarrhea, abdominal cramps, brown ring-shaped markings in eyes (Kayser-Fleischer rings), and jaundice 1.
Diagnostic Tests
- 24-hour urinary copper excretion: This test measures the amount of copper excreted in the urine over a 24-hour period. A level greater than 100 μg (1.6 μmol) is typically considered abnormal, but levels greater than 40 μg (0.6 μmol) may also indicate heavy metal poisoning and require further investigation 1.
- Penicillamine challenge test: This test involves administering a dose of penicillamine and then collecting a 24-hour urine sample to measure copper excretion. A level greater than 1600 μg (25 μmol) is considered indicative of heavy metal poisoning 1.
- Serum nonceruloplasmin-bound copper concentration: This test measures the amount of copper in the blood that is not bound to ceruloplasmin. A level greater than 25 μg/dL is considered abnormal, but this test is not always reliable and should be used in conjunction with other diagnostic tests 1.
Important Considerations
- The diagnosis of heavy metal poisoning should be made based on a comprehensive medical evaluation, including a thorough medical history, physical examination, and laboratory tests.
- The accuracy and reliability of diagnostic tests for heavy metal poisoning are debated, and no single test should be used as the sole basis for diagnosis or treatment.
- Treatment for heavy metal poisoning typically involves the use of chelating agents, such as penicillamine or succimer, to remove heavy metals from the body 1.
From the Research
Diagnosis of Heavy Metal Poisoning
The diagnosis of heavy metal poisoning involves a thorough evaluation of the patient's history, physical examination, and laboratory tests. According to 2, a thorough history, including detailed occupational and social histories, and a physical examination, with laboratory tests and imaging as needed, should be performed in cases of suspected exposure.
Laboratory Tests
Laboratory tests for heavy metal poisoning include urine tests, such as the urine mobilization test, challenge test, or provoked urine test, which involve the administration of a chelating agent to a person prior to collection of their urine to test for metals 3. However, the use of these tests is not recommended due to their lack of validation and potential harm 3, 4.
Chelation Challenge Tests
Chelation challenge tests, such as those using dimercaptosuccinic acid (DMSA), dimercaptopropanesulfonate (DMPS), and ethylenediaminetetraacetic acid (EDTA), are not supported by current evidence for the diagnosis of metal toxicity 3, 4. In fact, studies have shown that these tests are inaccurate predictors of heavy metal poisoning and can lead to false positives 4.
Key Points to Consider
- Heavy metal poisoning can occur through ingestion, inhalation, or skin absorption 2
- Exposure to heavy metals can have adverse health effects, varying by type and form of metal, exposure factors, and individual patient characteristics 2
- There is no standard, validated challenge test for heavy metal poisoning 3
- Chelation challenge tests are not recommended due to their lack of validation and potential harm 3, 4
- A thorough history, physical examination, and laboratory tests are necessary for the diagnosis of heavy metal poisoning 2