JERUSALEM — Medical experts warned yesterday that Prime Minister Sharon’s deteriorating condition could put his life in danger, while the hospital treating him said it would run more tests to find the cause of his downturn.

The Sheba Medical Center near Tel Aviv said Sunday that the former leader’s kidneys were failing and that changes were detected in his brain membrane. Mr. Sharon, 78, has been in a coma since suffering a severe stroke in January.

A hospital spokeswoman refused to say whether his life was threatened.

A cardiovascular expert at London’s University College, Dr. John Martin, said the kidney failure and the changes in the brain membrane that Mr. Sharon suffered in the past two days indicated the former leader’s life was in danger. His comments were echoed by other physicians quoted in Israeli press outlets.

Kidney dialysis and drugs to treat what appears to be cerebral edema could lead to an improvement in Mr. Sharon’s condition within hours, Dr. Martin said. But many physicians would choose not to take such steps when a patient has been in a coma for more than seven months, he added. “This is a significant decrease in his condition,” Dr. Martin told the Associated Press. “Shall we give dialysis or shall we let him die … most European physicians would consider this at this point.”