Apple CEO Tim Cook responded to the mother of a teenage girl in Lithia, Florida, who told him an Apple Watch saved her daughter's life.

In late April, Deanna Recktenwald’s Apple Watch notified her that her resting heart rate jumped to 160 beat per minute -- well over the normal range of 60 to 100 beat per minute.

"I didn't know what was going on at all and it was just out of the blue," Recktenwald, 18, told WFTS-TV.

Recktenwald's mother and registered nurse, Stacey, shared her daughter's health story in an email to Apple CEO Tim Cook. At first, Stacey explained in the email posted by WFTS-TV, she thought the reading was “just a fluke” because the 18-year-old is a “healthy, athletic young lady with no previous medical conditions."

But the teen’s heart rate continued to rise -- eventually reaching 190 beats per minute. At that point, Stacey took her daughter to a local urgent care to confirm the watch’s reading.

The urgent care confirmed Recktenwald's vitals were abnormal and suggested she go to the emergency room.

Shortly after, doctors discovered the teen was reportedly suffering from chronic kidney disease and she was in kidney failure.



“I didn't even know that it had the capability of giving us that alert,” Stacey said of the watch. She added in the letter that “if it wasn’t caught now the doctor said that she would have needed a kidney transplant."

“[I] Instantly started to pray and thank God for her having that watch," Recktenwald's father, Tom, told the news station.

Like most parents, Stacey is nervous about sending her daughter off to college in the fall, though she said it's comforting to know the teen will have an Apple Watch to help monitor her heart rate.

Cook replied to Stacey's letter on April 26, saying he was glad to hear Recktenwald is doing better and thanked the mother for sharing the story.

“This inspires us to keep pushing,” Cook replied.

Recktenwald was not immediately available for additional comment when contacted by Fox News on Wednesday.