LOS ANGELES (Reuters) – Selena Gomez said on Thursday that she has had a kidney transplant to treat the lupus that has derailed her life for more than three years

In an Instagram posting, the 25 year-old singer showed a photo of herself in the hospital lying next to her best friend, actress Francia Raisa, who she said made the “ultimate gift” of donating her kidney.

The “Good For You” singer explained in the post that she had been lying low this summer because “I found out I needed to get a kidney transplant due to my Lupus and was recovering. It was what I needed to do for my overall health.”

The singer, who has the biggest following on Instagram with 126 million followers, also posted images of a post-operative scar on her lower abdomen.

Gomez, who came to fame in Disney Channel’s “Wizards of Waverly Place” and dated singer Justin Bieber for several years, revealed in 2015 that she had been diagnosed with the auto-immune disease lupus and undergone chemotherapy to treat it.

The announcement followed two career breaks and a canceled tour. In 2016 she again canceled part of her tour, saying she was suffering from anxiety and panic attacks caused by lupus.

The cause of lupus is not clear and symptoms can include swollen joints, fatigue, rashes and fever.

“Lupus continues to be very misunderstood but progress is being made,” Gomez said in Thursday’s Instagram post

She thanked Raisa, best known for TV series “The Secret Life of the American Teenager,” for donating the kidney.

“There aren’t words to describe how I can possibly thank my beautiful friend,” she said. “She gave me the ultimate gift and sacrifice by donating her kidney to me. I am incredibly blessed. I love you so much sis.”