A fitness tracker could be more useful than just helping you shed weight — the data it's collecting about your body could go as far as saving lives.

73-year-old Patricia Lauder from Connecticut noticed her Fitbit data was logging an abnormally high resting heart rate of over 140 beats per minute, far higher than her usual 60 to 70, CNN reported.

She had already visited the doctor after a recent sinus infection and was waiting for results, but the data was alarming enough that she called 911 to be sent to the emergency ward.

They found blood clots in both lungs.

At the hospital, a scan revealed blood clots in both lungs, which were forcing her heart to work harder to compensate for the lower oxygen levels.

Left untreated, a large clot stopping blood flow in the lungs can be deadly.

She was treated for the clots and they were gone within 24 hours, with her lungs and heart returning to normal function.

Last year, a 42-year-old man's Fitbit Charge HR helped his doctors quickly decide on the appropriate treatment for him, because they could reference historical data from the app.

The app showed exactly when his heart rate jumped, so they could tell with more certainty what caused it.

While these wearables are certainly not meant to take the place of medical equipment, it's another data source that could alert you or your doctors to an irregularity that you may not have otherwise noticed.