A Connecticut woman is crediting her Fitbit with saving her life, after the device detected signs of life-threatening blood clots. The woman, 73-year-old Patricia Lauder, had recently retired and bought a Fitbit to help her get in shape, according to a statement from the University of Connecticut, where Lauder was treated. But then, she began to feel ill, even though doctors’ tests for health problems came back negative.

She also noticed that her heart-rate reading on her Fitbit was gradually increasing, until one day, it spiked to 140 beats per minute. She called 911 and was taken to the hospital, where tests showed that she had a condition called pulmonary embolisms, or blood clots in her lungs. Doctors gave her anti-clotting medication, which got rid of the clots. Experts say that, because some fitness trackers include heart rate monitors, the devices can potentially alert people to certain health problems that cause changes in heart rate. In September 2015, a high school senior credited his Apple Watch with saving his life, when the device showed he had a heart rate of 145 beats per minute. An exam revealed that he had rhabdomyolysis, a condition in which muscles release a protein that damages the kidneys and other organs.