A method, system and storage medium for providing an alarm for indicating that an abnormality is present in a sample analyzer are provided. The method includes: mixing a first aliquot of a blood sample with a diluent agent to prepare a first test sample; mixing a second aliquot of the blood sample with a lytic reagent to prepare a second test sample; detecting electrical impedance signals of the first test sample; detecting at least two types of optical signals of the second test sample; acquiring first platelet detection data based on the electrical impedance signals; acquiring second platelet detection data based on the at least two types of optical signals; acquiring an evaluation result based on a difference between the first platelet detection data and the second platelet detection data; determining whether the evaluation result meets a preset condition to provide an alarm.