A few hours after a US student tweeted "Thank you God for a nother year of life" on her 21st birthday, she collapsed and died.

Ariane Noelle Patterson was in a religious class at Gardner-Webb University in Boiling Springs, North Carolina, on Tuesday when she "lost consciousness after lunchtime", the Gaston Gazette newspaper reported.

Ariane Noelle Patterson ... died on her birthday. Credit:Facebook

Another student, who was a trained emergency medical technician, performed CPR on her until paramedics arrived, a spokesman for the university said.

Her classmates prayed for her in the hallway, spokesman Noel Manning added.