NEW YORK (CBSNewYork/AP) — Selena Gomez is revealing why she’s kept a low profile this summer.

The 25-year-old pop star said in an Instagram post that she received a kidney transplant due to her struggle with lupus and has been recovering from the procedure.

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Her best friend, television actress Francia Raisa, was her donor.

The Instagram post includes a picture of Gomez and Raisa holding hands while lying side-by-side in hospital beds. Gomez also posted a picture of a scar on her abdomen.

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

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Gomez, who revealed her lupus diagnosis in 2015, called the transplant “what I needed to do for my overall health.”

The post didn’t reveal Gomez’s current condition or say where or when the procedure took place.

Gomez’s publicist declined to release more information.

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