On Wednesday, April 20, 2011, there will be changes in determination of blood lead concentrations in the Clinical Chemistry Laboratory.  The lead testing methodology will shift from atomic absorption (AA) to the LeadCare II instrument.  This will allow for 24/7 availability of lead concentrations compared to the current schedule of routine testing performed only one day/week.

LeadCare II has now become the most widely used screening test for blood leads, in large part due to the ability to have rapid turnaround time while having good correlation with reference methods.  The test is orderable in Epic under the name “LEAD, BLOOD (BY LEADCARE II)” (Epic #LAB98).  Either venous sample (3 mL in lavender top tube) or capillary sample is acceptable.  It is recommended that patients at high risk for having elevated lead concentrations have a venous sample drawn.

Confirmatory testing requirements

By state of Iowa requirements, all lead concentrations of 15 μg/dL or greater by the LeadCare II instrument must be confirmed with a venous sample analyzed by a reference method such as atomic absorption or inductively-coupled plasma mass spectrometry (ICP-MS).  This requirement will be fulfilled by having the test “LEAD, VENOUS CONFIRMATION BY ICP-MS” (Epic #7479) available.  For the confirmatory test, only a venous specimen is acceptable (i.e., no capillary sample allowable).

Procedures for confirmatory testing

If the lead concentration is 15 μg/dL or greater by LeadCare II test and sufficient venous specimen is available for confirmatory testing, the Clinical Chemistry Laboratory will reflexively send out the confirmatory test.

If the lead concentration is 15 μg/dL or greater by LeadCare II but insufficient specimen is available for confirmatory testing (which includes all capillary samples), the ordering clinician will be contacted and informed of the state of Iowa requirement for obtaining a venous confirmatory specimen at a future visit. 

Lead concentrations in last 3 years

In the past 3 years, there were 16 patients tested in the Clinical Chemistry Laboratory that had blood lead concentrations of 15 μg/dL or greater.  In that time, there were only 2 patients that had venous lead concentrations exceeding 60 μg/dL.  Of the 3,283 specimens analyzed in the last 3 years, 3,170 (96.6%) had lead concentrations less than 5 μg/dL.  The LeadCare II is capable of determining lead concentrations up to 65 μg/dL.  Above 65 μg/dL, results will be reported as “> 65”.

Questions should be directed to Matthew Krasowski, MD, PhD, Medical Director of the Clinical Chemistry Laboratory (384-9380, matthew-krasowski@uiowa.edu).