Lead

What To Think About

• Blood tests for lead should be done by a lab experienced in proper technique. A finger stick or heel stick can test for lead poisoning but must be done carefully to prevent contamination of the sample from lead on the skin. Any result of 0.48 mcmol/L of lead or higher from a finger or heel stick should be rechecked on a blood sample drawn from a vein. Some doctors prefer to only test blood drawn from a vein. If a finger or heel stick are too high, a follow-up blood sample should be taken from a vein to double-check the results.
• Lead can also be measured in urine, although the amounts are normally very low. However, if you are being treated for lead poisoning with medicine (chelation therapy), your urine may be tested to keep track of the amount of lead being removed from your body. Urine tests for lead are done on a sample of urine collected over a 24-hour period.
  • A lead mobilization test may be done to decide whether to treat lead poisoning with chelation therapy. For this test, calcium disodium edetate (EDTA) is given intravenously or intramuscularly. Calcium disodium EDTA binds to lead, causing it to be removed from body tissues then excreted in the urine.
  • A urine aminolevulinic acid (ALA) test may be done to check the extent of lead poisoning. ALA is a substance the body uses to make hemoglobin, the oxygen-carrying protein in red blood cells. In lead poisoning, the production of hemoglobin is blocked, causing ALA to build up in the blood and to be passed into the urine. Because urine ALA levels do not increase until blood lead levels are high, the urine ALA test is not a good way to test for lead poisoning in children.
• The Canadian Centre for Occupational Health and Safety (CCOHS) requires companies to test the blood of employees who work with lead and to give employees written copies of any blood sample that shows a lead level of 1.92 mcmol/L or greater. CCOHS requires the employer to have the employee checked by a doctor for possible treatment if the employee has a blood lead level higher than 2.88 mcmol/L.
• Results need to be reported to the local health unit if 2 or more blood lead levels are above 0.48 mcmol/L. A home inspection is needed to find the source of the lead.

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Author:	Carrie Henley Sydney Youngerman-Cole, RN, BSN, RNC	Last Updated: September 26, 2006
Medical Review:	Michael J. Sexton, MD - Pediatrics Tom Bailey, MD - Family Medicine R. Steven Tharratt, MD, MPVM, FACP, FCCP - Pulmonology, Critical Care, Medical Toxicology
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