Tests for Lead Poisoning
A blood lead test can be done to determine the level of lead in the body. This is usually performed on a sample drawn from a vein in the arm but may sometimes be performed on a sample from a fingerstick or heelstick (for infants). If the fingerstick sample is abnormal, then it is frequently followed by a sample taken from a vein in the arm to confirm the findings. Blood lead levels are a snapshot of the amount of lead in the blood at that moment. They are the best test for detecting and evaluating recent acute and chronic exposure. Blood lead samples are used to screen for exposure and to monitor the effectiveness of treatment.
If a child's blood lead level is greater than 20 mcg/dL, the healthcare practitioner may order a hemoglobin and/or hematocrit test to determine if the child is anemic and may order iron tests to check for iron deficiency.
In adults, the zinc protoporphyrin (ZPP) test may be ordered, along with a lead level, to test for chronic lead exposure. Hobbyists who work with products containing lead and people who live in older houses may be at an increased risk of developing lead poisoning. In an industrial setting, the Occupational Safety & Health Administration (OSHA) mandates the use of the ZPP test and strongly recommends that a ZPP test be ordered every time that a lead level is ordered to monitor an employee's exposure to lead. Both are necessary because ZPP will not reflect recent or acute lead exposure and it does not change quickly when a person's source of lead exposure is removed. ZPP is best at detecting a person's average exposure to lead over the last 3-4 months. ZPP is not sensitive enough for use as a lead screening test in children, as values do not rise until lead concentrations exceed the acceptable range.