In assessing a 4-year-old boy with an attention deficit, what laboratory finding can confirm lead exposure?

In the context of assessing a child for lead exposure, the laboratory finding that confirms lead exposure is an increased serum lead concentration. Lead poisoning is a significant concern, especially in young children, due to their developing brains and bodies. When lead is absorbed into the body, it can be measured directly in the blood, and elevated levels indicate recent exposure.

Lead affects various physiological systems, and its presence can cause neurodevelopmental delays, cognitive impairments, and behavioral issues. The measurement of lead in blood is a standard and effective method for diagnosing lead toxicity, making increased serum lead concentration the definitive laboratory finding in this case.

Other options, such as increased serum ferritin, elevated hematocrit, and increased blood glucose levels, do not directly confirm lead exposure. Serum ferritin may be elevated in response to inflammation or chronic disease but is not specific to lead exposure. Hematocrit levels might change due to various reasons but are not indicative of lead toxicity. Blood glucose levels are also not related to lead exposure and can be influenced by many factors irrelevant to lead concentration in the body. Therefore, the confirmation of lead exposure is best achieved through increased serum lead concentration.