Bronny James has to undergo more tests so doctors can determine what caused his cardiac arrest, according to a new report.

Sources told TMZ Sports Wednesday that the 18-year-old athlete’s parents, LeBron James and Savannah James, are “relieved” that their eldest son is “doing much better” two days after being rushed to a Los Angeles hospital.

While the teen is now out of the intensive care unit, LeBron and Savannah are “anxious to know what caused Bronny’s heart to stop” but staying “optimistic,” per the outlet.

“They seem to have gotten enough reassurance from his doctors to tamp down the fear.”

Bronny James’ parents are “relieved” after his cardiac arrest.Getty

The 18-year-old was rushed to an LA hospital Monday.Getty Images

Photos obtained by Page Six exclusively showed the worried father arriving at Cedars-Sinai hospital Monday.

The Lakers legend, 38, was seen walking into the medical center wearing gray shorts and a white graphic T-shirt along with a protective face mask.

A spokesperson for the James family told us Tuesday that Bronny had suffered cardiac arrest during basketball practice at the University of Southern California.

The NBA legend was photographed arriving at Cedars-Sinai hospital.MEGA for NY Post

“He is now in stable condition and no longer in ICU,” the James family’s rep shared.Los Angeles Times via Getty Images

“Medical staff was able to treat Bronny and take him to the hospital. He is now in stable condition and no longer in ICU,” the rep shared.

“We ask for respect and privacy for the James family, and we will update media when there is more information.”

According to the American Heart Association, cardiac arrest occurs when the heart “malfunctions and stops beating unexpectedly.”

LeBron and his wife, Savannah James, are reportedly staying “optimistic.”Variety via Getty Images

The condition is different than a heart attack, which occurs when blood flow to the organ is blocked.