An extended range test strip includes a simple system where the end user can determine the concentration of the analyte at high concentration with a single drop of whole blood. A single drop of blood spreads across a spreading layer and into multiple reagent stacks. Multiple reagent stacks of the test strip may be configured to test for different ranges by adding a peroxide modulator. Readings from multiple reagent stacks producing a colorimetric response may be tested simultaneously. Working from the lowest range to the highest range of reagent stacks, the first reagent stack to be less than its maximum range is considered to be the reagent stack that is producing a colorimetric response related to the actual amount of analyte in the sample.