This test measures the amount of lead in a person's blood. Lead is a poisonous (toxic) metal that can damage the brain and other parts of the body. A lead blood test is done to: •Diagnose lead poisoning. •See how well treatment for lead poisoning is working. •Look for lead poisoning in people who work with lead or lead products or live in places where the chance of poisoning is high, such as in a large city. •Check the amount of lead in people who live with or play with children who have lead poisoning Blood tests for lead should be done by a lab experienced in proper technique.