Common Test-Ordering Errors
Part 5: Overordered Tests
Plasma Thiamin
Serum Folate
Zinc Protoporphyrin (ZPP)
Lead Toxicity

August 2010
The next issue I'd like to talk about is lead toxicity, as it relates to the overordered test zinc protoporphyrin or ZPP. While the ban on lead paint in the late 1970s greatly decreased the incidence of lead toxicity in our country, it did not eliminate it because lead-based paint is still present in some homes and lead toxicity remains a threat to children in the United States.
Lead can have adverse effects throughout the body, but it is especially harmful to the developing brain and nervous system of young children. It is estimated that a child's IQ will fall 1 to 3 points for every 10 mcg/dL increase in blood lead. However, even lead levels lower than 10 mcg/dL (which is the cut point that has been recommended for intervention) can be harmful.
A number of studies have demonstrated an association between learning difficulties, behavioral problems, and IQ and blood lead levels between 5 and 9 mcg/dL. Furthermore, according to the CDC "There is no safe level of lead in the blood. Any confirmed level of lead in the blood is a reliable indicator that the child has been exposed to lead." Consequently, it is important to have sensitive and specific tests available for all at risk children.
Lead Toxicity |
Jump to section:
- Introduction
- Testing at Mayo Medical Laboratories
- Common MML Test-Ordering Errors
- Overordered Tests
- Thiamin (Vitamin B1)
- Thiamin (Vitamin B1)
- Folate—Serum and RBC
- Diagnostic Algorithm for Macrocytic Anemia
- Simplified Versions of Vitamin-Dependent Pathways
- Lead Toxicity
- Heme Synthesis*
- Laboratory Assessment of Lead Toxicity
- Conclusion
- Questions?


