"Wow thank you for changing my life, and for being my friends. My overwhelming gratitude for you all will never end," she said.
Younger fans tweeted the Kiwi singer with pictures of fake tattoos.
"@lordemusic when you're underage but still love your work," said one user, with a picture of their wrist with "Pure Heroine" written in sharpie.
Her latest single Magnets was released last week and the song, a collaboration with British house music duo Disclosure, has already hit No. 1 on iTunes.
"Woah s***, top track on Apple music ... I'm genuinely chuffed," Lorde tweeted on Saturday.
Pure Heroine was released on September 27 in 2013 and has sold nearly three million copies.
Lorde, real name Ella Yelich-O'Connor, was just 16 when the album was released to mainly positive reviews.
The single Royals debuted at No. 1 on the New Zealand Top 40 in March 2013 and remained in the top position for three weeks.
-nzherald.co.nz