What is a characteristic finding in blood tests for lead poisoning?

In lead poisoning, one of the key laboratory findings is microcytic anemia accompanied by coarse basophilic stippling of red blood cells. The presence of basophilic stippling occurs due to the inhibition of enzymes involved in heme synthesis, such as aminolevulinic acid dehydratase (ALAD) and ferrochelatase. This inhibition leads to an accumulation of ribosomal RNA within the red blood cells, giving rise to the distinctive stippling seen on blood smears.

Microcytic anemia is characterized by the production of smaller than normal red blood cells, which occurs in lead poisoning due to the interference with hemoglobin synthesis. The combination of microcytic anemia and basophilic stippling in lead poisoning helps differentiate it from other types of anemia.

While other conditions may present with anemia, they lack the specific combination of microcytic anemia and basophilic stippling seen in lead toxicity. Thus, the presence of these findings in blood tests is a hallmark of lead poisoning.