Any excess or lack of human serum albumin (HSA) in urine should be considered a warning for renal or cardiovascular diseases. This report proposes a rapid and straightforward method for detecting HSA based on the surface plasmon resonance characteristics and sensitivity of antibody-functionalized gold nanorods (GNRs) to trace changes in the local environment. The role of potential parameters (e.g., pH, the concentration of antibody, and the blocking agent) was also studied to optimize the sensor performance. The nanobiosensor determined HSA in the 30–300 μg·mL−1 concentration range with a detection limit of 1 μg·mL−1 and exhibited high selectivity towards HSA. This nanobiosensor has a detection limit within the reference range required to detect microalbuminuria or macroalbuminuria. The developed nanobiosensor also showed the possibility of tracing HSA in urine samples with 95–100% accuracy. This investigation introduces a potential application of gold nanorod-based sensors as promising alternatives for conventional methods in the form of a new generation of facile, rapid, and "lab-in-a-vial" nanodiagnostic technique. [ABSTRACT FROM AUTHOR]