SAN FRANCISCO — Facebook’s addition of a way for its users to tell people their organ-donor status helped boost the number of people who registered as donors 21-fold in one day.

Two weeks after the social networking website set up the profile information on May 1, 2012, the rate of new organ donors was still climbing twice as fast as before, according to a paper published Tuesday in the American Journal of Transplantation.

Organ donation has long been an interest of Sheryl Sandberg, chief operating officer at Menlo Park, Calif.- based Facebook.