The Pentagon's top civilian health official is stepping down after more than five years on the job — an expected move as the Obama Aadministration enters its final months.

Dr. Jonathan Woodson, assistant secretary of defense for health affairs, has submitted his resignation effective May 1. He is expected to return to the private sector, where he previously served as associate dean for student diversity and multicultural affairs and associate professor of surgery at Boston University School of Medicine, and senior attending vascular surgeon at the Boston Medical Center.

An Army Reserve brigadier general, Woodson also has served as an adjunct assistant professor of surgery at the Uniformed Services University of the Sciences and deputy commander, Army Reserve Medical Command.

Woodson was confirmed as assistant secretary in December 2010. Under his tenure, the military health system embarked on major reform efforts designed to contain the Defense Department's $50 billion health budget.

Those initiatives include: creating a Defense Health Agency responsible for overseeing all military medical support, training, education and administrative services within the department; reducing the geographic areas served by Tricare Prime, the department's health maintenance organization-style health program; broadening the department's mail order pharmacy benefit to reduce prescription costs; and encouraging beneficiaries to receive medical care at military treatment facilities, considered the most cost-effective health care option for the department.

An avid runner, he also promoted preventive health programs and wellness, launching the Healthy Base Initiative, a demonstration project at 14 installations that focused on active lifestyles, tobacco-free living and healthful eating.

Woodson's replacement has not been named.

Patricia Kime covers military and veterans health care and medicine for Military Times. She can be reached at pkime@militarytimes.com