What is the most likely diagnosis for a child presenting with intermittent abdominal pain, peripheral neuropathy, irritability, and headaches?

The presentation of intermittent abdominal pain, peripheral neuropathy, irritability, and headaches in a child is highly suggestive of lead poisoning. Lead exposure can result in a wide range of neurological and gastrointestinal symptoms due to its toxic effects on the central nervous system and the body's ability to process nutrients.

Abdominal pain is a common gastrointestinal manifestation in lead poisoning, often associated with constipation or changes in bowel habits. Peripheral neuropathy occurs due to lead's neurotoxic effects, leading to symptoms such as weakness or sensory changes in the extremities. Irritability and headaches are also typical neurological symptoms associated with lead toxicity, often stemming from increased intracranial pressure or disruptions in normal brain functioning.

In contrast, while iron deficiency anemia might also cause fatigue and irritability, it does not typically manifest with peripheral neuropathy or recurrent abdominal pain in this manner. Vitamin D deficiency primarily results in bone pain and muscle weakness but does not explain the neurological symptoms. Hepatitis usually presents with signs of liver dysfunction, such as jaundice, but not with this particular constellation of symptoms. Thus, the combination of the described symptoms strongly points to lead poisoning as the most likely diagnosis.