Temple University Hospital's chief executive officer is stepping down and being replaced by an interim administrator from a consulting firm, Temple Health System president Larry Kaiser announced Friday.

Kaiser, who took over as head of the health system and dean of Temple University Medical School eight months ago, has been working to stem financial losses, add top medical talent, and reach beyond Temple's poor North Philadelphia neighborhood.

"As that effort continues to unfold," Kaiser wrote in a letter dated Friday, "Sandy Gomberg will step down as president and chief executive officer of Temple University Hospital."

John N. Kastanis, a health-care manager with Navigant, a business consulting firm headquartered in Chicago, will begin Dec. 19.

The Temple system, which includes the hospital on North Broad Street and Jeanes Hospital in Northeast Philadelphia, has long had economic challenges because of its disproportionate share of uninsured and publicly insured patients.

In recent years, the system has also grappled with cuts in Medicare reimbursements, the unpopular closing of money-losing Northeastern Hospital, and a long, bitter, and costly labor strike at Temple University Hospital in April 2010.

Operating losses for the fiscal year ending June 30, 2010, were $48 million, half that amount related to the cost of bringing in replacement nurses and health workers during the strike, according to the latest report on Temple by Moody's Investors Service.

For the most recent fiscal year, ending in June, the health system reported a bottom line just slightly in the black.

Moody's currently gives Temple's health system its lowest investment-grade rating - Baaa - and says "inability to improve current operating trajectory could result" in a downgrade.

Last year, Edmond Notebaert, who was head of the health system during the strike, stepped down, about nine months before Kaiser was appointed.

Gomberg, who was unavailable for an interview, held various administrative posts in the health system for 14 years, including the last three as head of the hospital. She "has agreed to remain available . . . to support this transition" to an interim executive, Kaiser wrote in his letter.

"Whoever runs that hospital has a difficult task from the revenue side," said Michael Rosko, a professor of health-care management at Widener University. "But there is room for improvement in virtually any hospital. I'm sure there are substantial opportunities to implement processes that are more efficient."

Tough times notwithstanding, since Kaiser's arrival the health system has recruited several nationally regarded surgeons, applied to reactivate its lung-transplant program, and expanded into the suburbs with the Temple Lung Center and Orthopaedics at Oaks, Montgomery County.

"We will continue that forward momentum," said health system spokeswoman Rebecca Harmon.

Contact staff writer Marie McCullough at 215-854-2720 or mmccullough@phillynews.com.