Heavy metals panels are used to screen for or to diagnose heavy metal poisoning in those who may have been acutely or chronically exposed to one or more heavy metals and to monitor excessive metal concentrations in those who work with various heavy metals. Testing is also conducted to monitor the efficacy of chelation therapy, a treatment to rid the body of high amounts of a heavy metal.
Panels are set up in groups of tests that mirror potential metal exposures. A laboratory may offer several different groupings that are specific for either blood or urine. A doctor will order the metals panel that corresponds to the person's occupation, hobby, suspected exposure, and/or clinical symptoms. Some of the metals that are more commonly tested include:
If the doctor suspects that someone has been exposed to a specific metal, such as lead, the doctor may order that specific test instead of, or in addition to, a panel. Lead is usually ordered by itself when screening for exposure, especially in children because of how susceptible they are to its effects. Some metals can also be measured in fluid, hair, fingernails, and body tissues. Usually these are ordered individually.
A heavy metals panel may be ordered if a doctor suspects that someone has been acutely or chronically exposed to one or more heavy metals. Signs and symptoms of heavy metal exposure will vary in nature and intensity depending on the type and quantity of metal involved; early symptoms of poisoning can be missed because they are often non-specific. Excessive exposure and damage to several different organs can occur even if a person has no, few, or nonspecific symptoms. Some signs and symptoms of metal poisoning may include:
Abdominal pain, nausea, vomiting, and diarrhea
Nervous system symptoms such as numbness, tingling of hands and feet, weakness
People who may be exposed to metals in the workplace are usually monitored periodically. Safety measures minimize risk to employees and help address problems when they are identified. The U.S. Occupational Safety and Health Administration (OSHA) regulates the use and monitoring of 35 toxic metals that may be found on the job. If excessive concentrations are detected, affected persons are monitored and steps are taken to reduce their exposure.
Care must be taken in the interpretation of heavy metals tests. A low level of a heavy metal in the blood does not necessarily mean that excessive exposure has not occurred. Heavy metals do not stay in the blood and will not be present in the urine for extended periods of time. Lead, for instance, migrates from the blood into the body's organs and over time is incorporated into the bones. If someone was chronically exposed to lead, then he might have lead in his blood, urine, organs, and bones.
Very low levels of many heavy metals may be present in the blood and urine of apparently healthy people because these metals are present throughout our environment. Recommendations for safe levels of heavy metals depend on the age of the person and may change over time as more information about their safety emerges.
Exposures to the same amounts and types of heavy metals will not necessarily lead to the same effects in different people because they absorb and eliminate metals at different rates. Those who have underlying health conditions may be more vulnerable than others to the same exposures.
Trace concentrations of heavy metals are monitored and minimized but are almost impossible to avoid altogether. For instance, naturally-occurring arsenic is a contaminant that can be found in some sources of drinking water throughout the world. Small amounts of mercury are found in fluorescent light bulbs and some thermometers. If these break, the mercury can be released. Methylmercury, an organic form of mercury that is produced by bacteria in water, can build up in fish over time. Concentrations vary regionally and with the size of the fish. The highest levels are typically found in bigger and older fish. In most cases, the benefits of eating fish outweigh the small risk of ingesting excess mercury. However, women who are pregnant may want to take extra precautions. The March of Dimes recommends that pregnant women avoid certain types of large fish during their pregnancy because of mercury's potential harm to the fetus.
Lead was once routinely used in paint, plumbing pipes, and as an additive in gasoline. In the U.S., these environmental sources of lead have decreased, but it can be present in the existing paint and plumbing of older homes. When lead house paint deteriorates, it creates lead chips and dust that can be stirred up with the movement of air and can find their way into the soil around the house. While anyone may be harmed by lead exposure, children are at the highest risk. They may eat paint chips, mouth painted surfaces, breath in lead dust, and play in contaminated soil.
In addition to lead, other heavy metals such as arsenic and cadmium have been found to contaminate some imported toys and jewelry. For information on safety standards for children's toys in the U.S., see the Consumer Product Safety Commission web site.
All of the sources of heavy metal exposure in the air, water, food supply, and in the environment are controlled, regulated, and monitored by three governmental agencies and the medical community. The Environmental Protection Agency (EPA) evaluates the effects of exposures, regulates industrial emissions, and establishes maximum contaminant levels for heavy metals such as arsenic in drinking water. The Food and Drug Association (FDA) establishes limits for metals in food, and the Centers for Disease Control and Prevention (CDC) recommends testing young children for lead, especially for those who live in or routinely visit a house built before 1978.
This article was last reviewed on May 30, 2013. | This article was last modified on May 30, 2013.
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