(Reuters) - The U.S. Food and Drug Administration said on Tuesday it has stopped all pediatric clinical trials of Amgen Inc's Sensipar after the reported death of a 14-year-old patient taking part in a study of the drug used to lower calcium levels in the blood. The agency said it was collecting information on the circumstances of the teenager's death. It said it does not know if the Amgen drug, used to lower dangerously high calcium levels in the blood, had any role in the death. ...