John Denys Blainey was professor of renal medicine at the University of Birmingham. He was born in Southampton, the son of Arthur Richard Blainey, a commissioned officer in the Australian Army. His mother, Joan née Cooke, was the daughter of an Anglican clergyman. He was educated at Queen Elizabeth’s School in Barnet, and then went on to study medicine at Middlesex Hospital Medical School.

He held house posts in Wolverhampton and Dudley, and then joined the medical branch of the RAF in 1946. He became a squadron leader and a graded specialist in pathology.

Following his demobilisation in 1948, he was a junior pathologist at Addenbrooke’s Hospital in Cambridge. In 1950 he was a medical registrar to the United Birmingham Hospitals, and in 1957 became consultant physician in Birmingham. He became honorary reader in renal medicine at the University of Birmingham in 1968, and honorary professor in 1977.

He wrote extensively on many aspects of renal disease and became the principal clinician of the investigative team led by John Squire during the 1950s; his colleagues in this period included John Hardwicke, physiologist and clinician; Douglas Brewer, pathologist; and John Soothill, immunologist. Together they performed a number of the landmark studies in renal disease during the 1950s, especially of proteinuria and the nephrotic syndrome, making use of the findings from the recently introduced technique of renal biopsy. In 1957 Denys spent time working in Chicago with one of the outstanding American groups interested in the same fields led by Robert Kark.

In the late 1950s he began working on haemodialysis for acute renal insufficiency, and in the early 1960s the Birmingham team now led by Blainey introduced the minicoil dialyser, which was popular for a while for acute as well as longer-term dialysis. When renal transplantation began in Birmingham in the late 1960s, Denys became the lead transplant physician, and published a number of papers on this and related subjects together with his surgical colleagues.

At the time of his election to the fellowship of the Royal College of Physicians in 1965 he listed music, woodworking and cabinet making, gardening, laboratory research and technology, and travel as his interests. In 1945 he married Myfanwy Davies, the daughter of a miner’s agent. They had a son and two daughters.