IOWA CITY, Iowa -- Iowa coach Kirk Ferentz said Friday that five of the 13 players hospitalized this week with a muscle disorder following grueling offseason workouts are being discharged.
Ferentz said in a statement that he's looking forward to the release of the eight remaining players "in the days ahead."
The coach hasn't spoken to reporters since the school announced Tuesday that the players had been hospitalized with rhabdomyolysis, a stress-induced syndrome that can damage cells and cause kidney problems.
Ferentz, whose son James is the starting center for the Hawkeyes, said he and members of his staff have been communicating with the players and their parents since learning they'd been admitted to the hospital.
"The health and well-being of each student-athlete in our football program is paramount. I will work with all of the individuals and groups that contribute to the welfare of our student-athletes to understand what led to this occurrence in order to make certain it does not happen again," Ferentz said.
University leaders announced Thursday that they've ordered an investigation into how the players wound up in the hospital, with Iowa Board of Regents President David Miles and school president Sally Mason saying the hospitalizations were "a cause for grave concern."
They agreed the university will have 90 days to complete an investigation analyzing events leading up to their hospitalization, and that the review will involve independent medical experts.
"Our entire staff shares the concern expressed by University of Iowa President Sally Mason and President David Miles of the Iowa Board of Regents and the State of Iowa, for the well-being and continued recovery of every student-athlete treated at University of Iowa Hospitals and Clinics," Ferentz said.
Also on Friday, University of Iowa Hospitals and Clinics officials said that medical records for some of the hospitalized football players may have been viewed by people who didn't have proper authorization.
University spokesman Tom Moore said a routine check by the hospital's information technology department indicated a potential breach of confidential information.
The players and their families were notified Friday of the matter, and officials say an investigation may take up to two weeks.
Earlier Friday, a parent confirmed to ESPN.com's Joe Schad that tests for illegal drugs administered to the 13 players came back negative, according to a parent briefed on the results.
According to a source, parents agreed to the testing that was recommended by a physician Tuesday. Tests were conducted Tuesday and Wednesday and results were revealed Thursday.
The players were hospitalized Monday and Iowa coach Kirk Ferentz returned from the recruiting trail to visit with the players and their parents on Wednesday.
According to one parent, Ferentz was "blistered" for not returning to Iowa sooner.
"Where were you?" one parent said he asked Ferentz. "How can you be out recruiting other kids? You sat in our living room and told us you'd take care of them."
The parent said Ferentz "was quiet. I believe he is devastated by all this. He has been wonderful. But his mistake was not coming off the road right away."
Iowa athletic director Gary Barta also has not commented on the matter. Barta did not immediately return a message Friday.
Some parents are blaming the intensity of a workout conducted Jan. 20 in which a strength and conditioning staff member had players do 100 squats at half their weight capability before pushing sleds.
According to a parent, after a three-week layoff following the Insight Bowl, this was the first workout the players were asked to do.
According to a parent, a strength coach said in a meeting before the sessions that the Hawkeyes had failed to finish games too often last season and that "we'll find out who wants to be here."
There were workouts Thursday and Friday, followed by two days off, then a request Monday for more squats, which resulted in such soreness and cramping that it led to the hospitalizations.
Rupert Galvez, a Denver doctor who specializes in sports medicine, helped treat seven University of South Carolina swimmers for similar symptoms as a medical fellow and wrote a 2008 paper about their case in the Clinical Journal of Sports Medicine warning coaches to avoid the same problem with rigorous workouts after extended layoffs.
Like the 13 Iowa football players, the swimmers had rhabdomyoloysis, which involves the release of muscle fibers into the bloodstream and can cause kidney damage. Extreme physical exertion is one of several causes of the disorder.
In the South Carolina case, Galvez said the male and female swimmers were among 41 student-athletes who participated in an intense training program that involved pushups, squats and weightlifting after they returned from summer break in 2007. After a few days, some of them were complaining of swelling and weakness in their biceps and triceps and discolored urine.
Galvez said seven swimmers were sent to the hospital to recover and rehydrate and were discharged after three or four days of treatment to rejoin the team. Galvez said he remains somewhat baffled why those individuals were affected by the disorder while others were not. He said those affected were not taking supplements and did not have underlying medical conditions that may have exacerbated the disorder.
One Iowa parent said some players had gained 30 to 50 pounds since entering the hospital because of the amount of fluids that have been forced into their bodies.
The parent said that one player was told he had sustained "20 to 30 percent loss of kidney function and that the damage may or may not be repaired."
Information from ESPN.com's Joe Schad, ESPN.com's Adam Rittenberg and The Associated Press was used in this report.