Urine and blood testing are both useful for assessing heavy metal exposure and toxicity, but each has its strengths and limitations. Urine testing measures both recent and ongoing exposure to heavy metals, and can provide information about the body's ability to eliminate metals. Urine testing can also detect some metals that may not show up in blood tests, such as aluminum and nickel.
It is important to note that urine testing alone may not be sufficient for diagnosing heavy metal toxicity. Other tests and assessments may be necessary, and the results of urine testing should be interpreted in the context of a person's overall health and medical history.