A 5-year-old child ingests 50 iron tablets, each with 27 mg of iron. Within 6 hours the child develops abdominal pain
and lethargy. On physical examination he is hypotensive. Laboratory studies show metabolic acidosis. Through formation
of which of the following compounds is the cell injury in this child most likely mediated?
Ans : C Hydroxyl radical
Excessive iron ingestion, particularly in a child, can overwhelm the bodys ability to bind the absorbed free iron with the transport protein transferrin.
The free iron contributes to generation of free radicals via the Fenton reaction. Ascorbic acid (vitamin C) and vitamin E both act as antioxidants to protect against free radical injury.
Hemosiderin is a storage form of iron from excess local or systemic accumulation of ferritin, and by itself does not cause cell injury until large amounts are present, as with hemochromatosis.
Nitric oxide generated within macrophages can be utilized to kill microbes. It can be converted to a highly reactive peroxynitrite anion.
Superoxide dismutase helps break down superoxide anion to hydrogen peroxide, thus scavenging free radicals.