Sydney Weston, 8, from Missouri, died from undiagnosed Addison's disease after experiencing a medical emergency during a flight to Chicago, officials reported.
She died on June 13, just after the airplane was redirected to Peoria due to a medical emergency.
Peoria County Coroner Jamie Harwood told PEOPLE that Weston's death "was determined to be the result of an adrenal crisis secondary to Addison's disease, a condition characterized by chronic adrenal insufficiency." Harwood noted that the condition was unknown "until the postmortem examination," suggesting that Weston's parents were likely unaware of her illness.
The coroner explained that Addison's disease can be difficult to detect in young patients. "Addison's disease can present insidiously in adolescents, with early symptoms such as fatigue, hyperpigmentation and unexplained weight loss often being subtle," Harwood said.
Weston's condition became more complex due to several infections, which included Streptococcus pyogenes, chronic duodenitis, and thyroiditis. These infections triggered an "acute adrenal insufficiency" crisis, leading to a rapid decline in her condition during the flight.
The SkyWest Airlines flight made an emergency landing in Peoria, Illinois, after Weston became unresponsive. Upon landing, she had no pulse and was not breathing. Emergency personnel transported her to a nearby medical facility, where she was pronounced dead at 8:05 a.m. local time.
Harwood explained the physiological process that led to Weston's sudden deterioration. "The body's demand for cortisol increases substantially during infections, and in Sydney's case, the inability of her compromised adrenal glands to meet this demand led to a rapid deterioration," he said.
Dr. Amanda Youmans, a board-certified forensic pathologist, carried out the examination. After Weston passed away, her family found out that her 11-year-old brother, Evan, also had Addison's disease.
Rebecca Lichtenberg, the organizer of the family's GoFundMe campaign, wrote, "Our primary focus now is on Evan and ensuring his well-being. We are dedicated to managing his health and conducting genetic testing for our family to deepen our understanding and trace the impacts for our health."
Harwood, a father of three, expressed his sympathy for the family's loss, stating, "I cannot even imagine the heartache for this poor family. Her death was nothing short of a tragedy."