House lawmakers said Tuesday that they will conduct a three-day series of hearings next week to look at how the Food and Drug Administration should regulate medical applications on smartphones and tablets. Lawmakers from the House Energy and Commerce committee will look specifically at how regulation affects patients, physicians and developers looking to capitalize on the growing field of mobile health and medical apps. The hearings follow a letter the committee sent to the FDA earlier this month, in which lawmakers questioned whether the Patient Protection and Affordable Care Act could allow the FDA to define smartphones and tablets with health-related apps as “medical devices” — and levy new taxes on developers and smartphone makers under the health-care law. That’s been a concern for developers, who often operate with very narrow margins, said Rep. Marsha Blackburn (R-Tenn.), the committee’s vice chairman. Blackburn said she’s concerned that the possibility of these taxes could discourage developers from making health-related apps.