The deaths from acute kidney injury could be prevented by simple steps such as nurses ensuring patients have enough to drink and doctors reviewing their medication, the researchers say.
Between 15,000 and 40,000 patients die annually because hospital staff fail to diagnose the treatable kidney problem, a figure that dwarfs the death toll from superbugs like MRSA.
The report comes less than a year after the NHS watchdog NICE was forced to issue guidelines on giving patients water after it found that 42,000 deaths a year could be avoided if staff ensured the sick were hydrated.
It highlighted how old and vulnerable patients can be left on wards without fluids, quickly becoming too weak from dehydration to request a drink from nurses, which hastens their deterioration.
The latest research said the condition, often called “the silent killer” because it goes unnoticed by medical staff, may affect as many as one in seven hospital patients and costs the NHS £1 billion a year.