''Her experience and skill in dialysis nursing is almost irreplaceable,'' he said.
''Her depth of knowledge, ability to deal with patients and their training to enable them to dialyse at home is second to none.
''It is a complex area and Maree's expertise is among the best in the world in the field of home dialysis.
''She is going to be extremely hard to try to replace. Her job description could be filled by three people doing the work that she's been doing.
''There have been some difficult times. That goes with the health system. Resource constraints can put pressure on the delivery of any service but Maree has made sure there has always been high quality care for dialysis patients.''
Prof Walker described Ms McDonald as an ''outstanding person''.
''She has excellent leadership skills and a great rapport with the patients and their families. Dialysis has a major impact also on families and their caregivers.
''Maree has had a big involvement in setting up a support group and in setting up holiday facilities for patients in Cromwell and later Clyde.
''She has gone well beyond the call of duty. It is almost unthinkable to have a dialysis unit without Maree but we have to move on and we are lucky to still have an excellent group of nurses. We just have to find someone to step into Maree's very large shoes.
''Our emphasis is very much on home dialysis. The rest of the world looks with envy upon Dunedin and Christchurch as to how we achieve that. The goal is to enable patients to be able to dialyse at home, to be independent and to be able to return to work.
''In most places in the world, patients become quite institutionalised. Our patients are able to lead a much more normal life, and Maree has been a huge part of that. Hospitals elsewhere in the world are trying to replicate what we do.''
Jock Allison, well-known Dunedin agricultural scientist and agri-business consultant who received a transplant seven years ago after almost three years on dialysis, echoed Prof Walker's comments.
''She is just fantastic, as far as the patients are concerned,'' he said.
''She has brought total professionalism and competence to her job without raising her voice.
''We've been extremely fortunate in Otago and Southland. Maree's an outstanding person and, as a patient, I always had complete confidence in her judgement.
''It's been much more than a job to her. It's been her life, really. She's done a lot of work outside hospital hours.
''Her record of service will be hard to beat. She is one of the very special medical staff that I have known.''
