By one way of figuring, Thomas Jefferson University Hospital in Philadelphia made a 22.8 percent profit on its medicare inpatients last year.

By another, the overall Medicare profit was only 8.1 percent.

How can two people looking at the same figures come up with such different bottom lines? The answer lies in the complex world of hospital accounting.

The 22.8 percent figure is reached by following the method of Health and Human Services Inspector General Richard P. Kusserow. It is based on costs, as defined by Medicare, of $39 million to serve inpatients, and Medicare payments of $50.5 million, for a profit of $11.5 million.

The 8.1 percent figure comes from the hospital's assistant executive director for finance, Mark Richards. Richards contends that the federal calculation ignores a long list of other Medicare costs and payments.

On the cost side, Richards said, the hospital spends $22.2 million on Medicare-related capital, medical education, outpatient services and certain other items. The federal figures also underestimate real care costs by about $5.6 million -- because Medicare does not pay its fair share of charity care and bad debt, and underpays on insurance, nursing care and certain other items. This brings total costs to $66.8 million.

On the income side, in addition to the $50.5 million it got for inpatient operating costs from Medicare, Richards said, Jefferson was reimbursed for the $22.2 million in other Medicare-related costs. This brings total revenues to $72.7 million.

The bottom line: When all these added factors are included in the calculation, according to Richards, total hospital profits are $5.9 million (not $11.5 million), or 8.1 percent (not 22.8 percent).