Common Test-Ordering Errors
Part 5: Overordered Tests
Plasma Thiamin
Serum Folate
Zinc Protoporphyrin (ZPP)
Simplified Versions of Vitamin-Dependent Pathways
August 2010
This next slide shows simplified versions of 2 vitamin-dependent pathways. The first involves both folate and B12; and the second involves B12 only. I show these, not only because disturbances in these pathways are central to the pathologic changes that occur in folate and B12 deficiencies, but also to demonstrate how homocysteine and methylmalonic acid levels can help determine the cause of megaloblastic anemia.
In B12 deficiency, both homocysteine and methylmalonic acid concentrations are increased; whereas in folate deficiency, only homocysteine is increased and MMA is normal.
Simplified Versions of Pathways |
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?
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