Is High Dosage Of Iron Tablets Advisable For A Child?

I take care of a 13 year old girl and her dad just emailed me that her doctor just let him know that she needs 2 tablets a day of 324 mg of iron. This seems like a very high amount and knowing what it does to a persons bowel movements. I m suppose to pick them up after I pick her up from school and start her on them right away. Help...what do I do??? Lee ( YYYY@YYYY )