Protoporphyrin levels >100 mg/dl indicates:
Iron overload
Lead poisoning
Porphyria
All of the above
Protoporphyrin is an intermediate in the pathway to heme synthesis. Under conditions in which heme synthesis is impaired, protoporphyrin accumulates within the red cell. This reflects an inadequate iron supply to erythroid precursors to suppo haemoglobin synthesis. Normal values are <30 mg/dL of red cells. In iron deficiency, values in excess of 100 mg/dL are seen. The most common causes of increased red cell protoporphyrin levels are absolute or relative iron deficiency and lead poisoning. Ref: Harrison's principle of internal medicine 17th edition, chapter 98.