Dr Prasit Watanapa, dean of the Faculty of Medicine Siriraj Hospital, announced that Kaewkwan, who had been admitted to the hospital with a myocardial infarction, passed away at 10.02am Thursday after a sudden heart attack.
Kaewkwan had served as Royal Household Bureau secretary-general since 1987.
In addition to his duties with the Royal family, he was also chairman of the Suntaraporn Foundation committee.