The Obama administration is tearing down barriers that make it difficult for patients to get access to their own medical records, telling doctors and hospitals that in most cases they must provide copies of these records within 30 days of receiving a request. In theory, patients have long had a right to obtain copies of their records, but federal officials say they receive large numbers of complaints from consumers frustrated in trying to exercise that right. In new guidelines, issued this month, the administration says doctors and hospitals cannot require patients to state a reason for requesting their records, and cannot deny access out of a general concern that patients might be upset by the information.