LEWISTON, Maine — Positions are being eliminated, departing employees are not being replaced and layoffs are expected as St. Mary’s Health System undergoes restructuring.

A source said as many as 25 people could be laid off at St. Mary’s Regional Medical Center, but a spokesman described that number as “fluid.”

Lee Myles, president and CEO of St. Mary’s Health System, released a statement late in the day Thursday to announce the restructuring.

“In order to prepare for health reform and make adjustments for reductions of MaineCare reimbursement, St. Mary’s Health System is undergoing a strategic restructuring,” Myles said in the statement. “As of today, the state owes St. Mary’s $23 million for services provided dating as far back as 2009. Given our current economy and changes in the national health-care structure, we can no longer absorb this outstanding debt. The purpose of restructuring is to reduce operating expenditures while optimizing patient care to meet the future needs of the community.”

According to the statement, hospital administrators are trying to find creative ways to ease the impact of lost jobs and eliminated positions.

“The actual number of impacted people is fluid as we progress through this transformation,” Myles wrote. “The cuts and changes have been thoughtful and targeted rather than a simple workforce reduction. We have not been filling open positions. Wherever possible, we are trying to fill positions with affected employees based on their skills. In the process, some positions are being eliminated entirely and we are losing valued colleagues and friends as a result.”

According to the source, the recent layoffs at the hospital include a woman who has been employed at St. Mary’s for 35 years.

“We realize that change is always difficult,” Myles wrote in the statement, “but it is necessary in order to meet the health needs of our community well into the future.”