Alere's INRatio and INRatio 2PT/INR Monitor System and INRatio Test Strips, used to measure how quickly a patient's blood clots, was recalled by the Food and Drug Administration last month. 

The test strips are used to measure a patient's blood clots (Prothrombin Time) when taking warfarin, a blood-thinning medicine; and the International Normalized Ratio test is used to compare the results of the patient's Prothrombin Time (PT), how long it takes the blood to clot, according to a news release.

The FDA found that the tests were providing falsely low results, sparking the recall. It was also misreading certain medical conditions including anemia, conditions associated with elevated fibrinogen levels, or unusual bleeding or bruising.

The Class I recall, the most serious kind of recall, comes after Alere received 18,924 reports of incidents in which the device has malfunctioned - including 14 serious injuries. When the device malfunctions it can lead to delayed treatment and cause severe or life-threatening injuries, including death. 

Alere is recalling all devices manufactured and distributed between April 1, 2008 to December 4, 2014. 

The company is not expecting the recall to lead to a device shortage. 

A correction letter was sent to patients with the device, as well as the doctors explaining the details of the recall. You can read the patient issued one here and the doctor issued one here