Federal health regulators say they have halted Amgen's studies of its thyroid drug Sensipar after the death of a 14-year-old patient in a company trial.
The Food and Drug Administration says it is gathering information about the death, but has shut down all studies of the drug in children.
Sensipar is approved for adults to treat over-activity of the parathyroid gland. Amgen Inc. had been studying the drug to see whether it works in children.
The FDA says in a statement it is unclear whether Amgen's drug had a role in the patient's death, but it is reminding doctors to prescribe it carefully.
The agency says doctors should monitor patients' calcium levels to make sure they don't fall to dangerous levels.