Mayhew, who was on the sidelines for 131 All Blacks tests, has been the team doctor for the Warriors for most of the past decade. He became an Officer of the NZ Order of Merit for his services to sports medicine in the New Years Honours List.
Among the sportspeople he became close to was late All Blacks superstar Jonah Lomu, who suffered from a kidney disorder that contributed to his death, aged 40, in November.
Mayhew, a pallbearer at Lomu's Eden Park memorial service, said at the time he always admired Lomu for his courage in pushing on with his rugby career despite serious health setbacks.
Mayhew's family have asked for privacy.