FDA's experts said Thursday that patients complaining of pain and other symptoms should get regular X-rays and blood testing for metal levels. However, panelists pointed out the problems with the accuracy of blood tests and the difficulties of interpreting the results. There are no standard diagnostic kits for sale that test for chromium and other metalsFor patients who are not experiencing pain, panelists said annual X-rays would be sufficient to monitor their implants. If the FDA ultimately follows the group's advice, U.S. recommendations would be less involved than those already in place overseas. Earlier this year U.K. regulators recommend that all people who have the implants get yearly blood tests to make sure no dangerous metals are seeping into their bodies. FDA regulators have suggested they want to take more time to sort out the differences between various implants and patient groups before making recommendations. "The truth is there are different types of hips and different types of patients," said Dr. William Maisel, FDA's chief scientist for devices, in an interview last week. "Understanding the characteristics of patients who experience adverse events is very important." Women and overweight people are among the groups that are more likely to have an implant failure. With little definitive data on U.S. hip implants, the agency has asked manufacturers like Johnson & Johnson, Zimmer Holdings Inc. and Biomet Inc. to conduct long-term, follow-up studies of more than 100 metal-on-metal hips on the U.S. market. FDA scientists say the studies will help "fill in the blanks" on a number of scientific questions, including the long-term effects of metal particles. But public health advocates say it could take a decade before that information is available. "Keeping these metal-on-metal hips on the market for the next five to 10 years while research is conducted is not ethical," said Diana Zuckerman, president of the National Research Center for Women & Families, during a public comment session at the meeting. "If the companies want to sell metal-on-metal hips, they should be required to prove their safety first."