A diagnostic method and associated test kit for detecting an analyte residing in a test sample is provided. The kit includes a housing, and a membrane disposed within the housing having a detection region and a collection region. A blood sample meter is provided having a first end for absorption of a blood sample, a filtering section adjacent to the first end that filters red blood cell components from the blood sample, and a storage section adjacent to the filtering section that receives plasma or serum from the filtering section. An opening in the housing is sized for insertion of the sample meter into the housing such that the storage section of the sample meter is disposed in fluid communication with the collection region of the membrane. The plasma or serum is transferred from the storage section of the sample meter to the collection region of the membrane for subsequent migration to the detection region.