Exploring a Non-Invasive Method for Simultaneous Measurement of Urinary Uric Acid and Creatinine Using Spectrophotometry

Gout is the most common type of inflammatory arthritis for adults worldwide. Uric acid and creatinine are key metabolic biomarkers for gout, of which the levels in the urine are useful for identifying the cause and monitor the condition, as well as for predicting painful acute gout attacks. Despite advances in spectrophotometric methods for the measurement of each metabolite in urine, a method for the simultaneous measurement of both using simple absorbance spectrophotometry has not yet been established. This project aimed to explore the feasibility of applying spectrophotometric methods to detect both biomarkers non-invasively in urine, with further goals of device development.

Spectroscopic experiments were carried out for uric acid and creatinine aqueous solutions, identifying 1141 nm and 1740 nm as potential wavelengths usable for differential spectrophotometry. A benchtop spectrophotometer was developed, and sample absorbance was measured for the two wavelengths. The signal at 1141 nm was demonstrated to follow increase in concentration, whereas the SNR for 1740 nm signal was determined to be insufficient with the current experimental setup and component choice. A portable device prototype for patient use was developed and functionality was demonstrated. Future improvements on wavelength choice, experimentation, design choices and SNR improvements are discussed.