Different diseases are detected by heel blood, such as the three diseases screened for in newborns, namely phenylketonuria, cretinism and sericea, each using different methods, such as congenital hypothyroidism using a time-resolved immunofluorescence test, while sericea and phenylketonuria use a fluorescence analysis method, and in some places dried heel blood slices are used for deafness genetic testing. Currently, heel blood is also used to detect a variety of hereditary metabolic diseases in newborns, and the substances are differentiated by the ratio between the mass and charge of the substance, using mass spectrometry. The current detection methods for heel blood are focused on three categories, namely time-resolved immunofluorescence detection techniques, fluorescence analysis, and mass spectrometry.