The university made the announcement Saturday.
Head track and field coach Fred Harvey says Urreiztieta was part of the Wildcat family and had a passion for the sport and for life. Harvey extended his condolences to the student's family.
The university did not release any details about the condition that led to the junior having surgery.
Urreiztieta was a graduate of Canyon del Oro High School. At UA, he competed in hurdles and twice earned academic all-conference honors.
In 2012, he clocked a personal best of 8.37 in the 60-meter hurdles. At the Pac-12 Championships, he posted a personal best of 14.62 in the 110-meter hurdles to take ninth place in the preliminary round.