Christina Applegate's daughter Sadie, 13, reveals health disorder diagnosis

Actress Christina Applegate's daughter Sadie Grace Applegate LeNoble revealed on her mother's podcast that she has been diagnosed with a disorder called POTS.

"I have something called POTS – postural orthostatic tachycardia syndrome," the 13-year-old said in the June 25 episode of the "MeSsy with Christina Applegate & Jamie-Lynn Sigler" podcast, titled "Sadie."

"When I stand up, I get really, really dizzy and my legs get really weak and I feel like i'm going to pass out and I have fainted before and I have gone unconscious," Sadie said of her symptoms. "But that doesn't usually happen, that's only on really bad days when it's hot out."

POTS or postural orthostatic tachycardia syndrome is marked by an abnormal increase of the heart rate, lightheadedness or fainting, according to the National Institute of Neurological Disorders and Stroke. The main symptom of POTS is that not enough blood returns to the heart when someone with POTS stands up after lying down.

According to the NINDS, the cause of POTS is currently unknown and anyone can develop POTS but young women and women between the ages of 15 and 50 are more likely to develop it and it can cause people to avoid exercising in order to prevent dizziness or fainting spells.

Sadie said she was diagnosed with the condition earlier this spring, about two to three months ago, but has lived with the symptoms for "a long time."

"Last year in sixth grade, I would go to the nurse multiple times a day for it because I always felt like I was going to pass out in class if I were to stand up and I'd be like, 'I have to go to the nurse. I can't do this.' Or I'll be in P.E. and I'll be like, 'I have to go to the nurse,'" Sadie recalled.

The teen said every time she would visit the nurse's office, staff there would dismiss her and her symptoms and assumed she was lying about her condition to miss class.

"They were like, 'You're doing this to get out of class. It's probably just anxiety. Go back to class,'" Sadie continued. "They wouldn't do anything for it and that definitely was hard because it was like, I genuinely felt so sick and I was in a lot of pain and them not doing anything about it definitely hurt me physically and emotionally because I was just like, 'This is rude. I feel sick and you are telling me to go to P.E. and run laps around the football field. I can't do that."

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The NINDS notes that POTS symptoms are treated in various ways and may include medications but symptoms can also persist for years. The federal health agency encourages anyone with POTS to volunteer for clinical trials and support further research into the disorder.

Sadie said dealing with POTS symptoms has helped her empathize with her mom's symptoms of multiple sclerosis or MS, which Applegate was diagnosed with back in 2021.

"When my mom's like, 'Oh, I'm kind of in pain right now. Oh, I'm having tremors.' If I didn't have this, I probably would be like, 'I don't really care. I don't know what you're talking about,'" she added.