Most of the NIH patients had the onset of MEN1 in the third decade (mean age, 29.3 yr) with the development of signs and symptoms of HPT, although about 40% presented with symptoms of ZES, as reported in other studies.31,140,378,387,444 However, there was an average delay of almost 9 years in establishing the diagnosis of MEN1 (mean, 38.2 yr) (see Table 1). Patients were followed to their last evaluation or death for an average of almost 25 years (average, 24.4 yr) and for 15.5 years from their diagnosis. Patients had an average age of 53.9 years at the last follow-up; however, this varied widely from age 27 to 80.6 years at the last visit.