Twenty-two former Grady dialysis patients have been left in medical jeopardy after an agreement for their treatment expired Wednesday.

Under that contract, Grady Memorial Hospital paid Fresenius Medical Care $750,000 for a year’s care of the uninsured immigrants. The patients are not U.S. citizens, and most are not in the country legally.

The immigrant group was left in limbo when Grady, Atlanta’s largest safety-net hospital, closed its outpatient dialysis clinic in 2009 after steep financial losses.

Just today, a dozen of the immigrants went to a Fresenius clinic in Atlanta for dialysis treatment, only to be turned away, a patient advocate said.

A Fresenius spokeswoman said the clinic directed the patients to Grady to receive care.

Massachusetts-based Fresenius sent a letter to the patients, dated Aug. 25, saying that as of Sept. 1, “you will need to return to Grady Hospital for your treatments.’’

Grady and Fresenius had been in negotiations on continuing the hospital’s payments for dialysis care of the immigrants, but the talks failed to produce a new agreement.

Grady’s recent financial slide is clearly a major factor in the situation.

A Grady spokesman, Matt Gove, said the hospital has lost $20 million so far this year, while Fresenius Medical Care had net income last year of about $1 billion.

Grady has made its ”best, final offer,’’ Gove said. “We’ve made a reasonable offer to help move beyond this.’’

But he also said, “These are Fresenius’ patients. They’ve been under Fresenius’ care for two years.’’

Fresenius said negotiations have broken off. “We endeavored to negotiate in good faith,’’ said company spokeswoman Jane Kramer in a statement. “A member of senior management at Grady said that the patients could come to the ER and be treated like other patients.’’

Gove noted that Grady no longer provides outpatient dialysis care, but he said that if patients show up in the emergency room in immediate need of care, “we’ll treat them.’’

“We have told [Fresenius] to direct patients to their nearest ER, not to Grady specifically,’’ he added.

Dorothy Leone-Glasser, an advocate for the dialysis patients, said three are critically ill. “Most of them will start to feel sick by Saturday.’’

“It seems cruel and inhumane,’’ said Leone-Glasser, a nurse who is president of the consumer group Advocates for Responsible Care. “This is a human rights issue. We’re going to start having catastrophes here.’’

Grady and Fresenius “need to work this out,’’ she said.

Patients need dialysis when they develop end-stage kidney failure — usually by the time they lose almost all kidney function.

Dialysis uses a man-made filter to remove wastes from the blood, restore a proper balance of electrolytes, and eliminate extra fluid from the body.

Typically, patients need regular dialysis three times a week.

Medicare covers routine dialysis, but illegal immigrants are not eligible for that federal insurance program, and neither are some newly arrived legal immigrants.

A year ago, Fresenius Medical Care agreed to treat 25 of the 38 end-stage renal disease patients at Grady’s expense, and treat five others as charity care cases. Emory Healthcare agreed to serve three more immigrants as charity, and Colorado-based DaVita said it would serve the other five as charity.

One of the 25 Fresenius patients has received health insurance, one has left the country, and another has discontinued treatment, the company said.