My grown-up son went fora CAT scan as he was troubled with kidney stones. This complaint has now cleared up but he is left feeling run-down and without energy. Could this be a result of the scan? He's normally fit and well; doesn't smoke and only drinks moderately.

I think it's extremely unlikely that a general feeling of malaise is caused by a CAT scan. (For what it's worth, my PhD was about the effects of radiation upon the body.) Short term effects would normally include nausea and vomiting, shortly followed by diarrhea and possibly fever, then headache. Weakness and fatigue are possible effects, but for lowish doses of radiation (and I can't really imagine that a CAT scan would provide a high dose of radiation), then symptoms would take about a month to appear.

In short, the symptoms are, in my opinion, either unrelated or psychosomatic.

I think it's extremely unlikely that a general feeling of malaise is caused by a CAT scan. (For what it's worth, my PhD was about the effects of radiation upon the body.) Short term effects would normally include nausea and vomiting, shortly followed by diarrhea and possibly fever, then headache. Weakness and fatigue are possible effects, but for lowish doses of radiation (and I can't really imagine that a CAT scan would provide a high dose of radiation), then symptoms would take about a month to appear.

In short, the symptoms are, in my opinion, either unrelated or psychosomatic.

Thanks for that AyG, my son will be much relieved.

Definitely not due to radiation from the scan per se but if it were a scan with contrast material injected intravenously it could be related to adverse effects of the contrast material. I've seen a number of people react to contrast media in various ways though I can't say "run down and lethargic" were amoing them, and these are pretty vague symptoms which can be attributed to many, many things.

Was he given strong pain killers for the kidney stones? (Often done during the acute phase of passing the stones). if so that may your answer.

Apparently a CAT scan is equivalent to ca 80 X-rays so not something you want to do too often.