The potential of spectral urine analysis in non-invasive diagnostics is exciting. Traditional testing methods have a place in diagnostics, but they often fall short in speed, precision, and scope. This is a significant drawback in settings where early detection is vital, especially in oncology. With the rise of liquid biopsy, particularly the focus on urine analysis, new possibilities are emerging in medical diagnostics.
Why choose urine?
Urine presents a unique opportunity for diagnostics. It’s non-invasive, easily accessible, and reveals critical insights into our metabolic state. As a reflection of both inflammatory and neoplastic processes, urine analysis can uncover vital biomarkers and metabolites, making it an ideal candidate for spectral diagnostic methods.
Limitations of traditional urine analysis
Historically, urine analysis has been a cornerstone of diagnostic medicine, but traditional methods come with inherent limitations in speed, accuracy and ability.
Culture tests are standard for detecting infections but require lengthy incubation periods of 24–72 hours, delaying diagnosis. Dipstick tests, on the other hand, detect a range of parameters such as pH, glucose, protein, ketones, bilirubin, and blood. They are quick and user-friendly. Unfortunately, these tests are semi-quantitative and prone to user error, limiting their reliability.
The technique of urine microscopy is used to detect cells (RBCs, WBCs), casts, crystals, and bacteria. It does provide helpful information; however, it is labour-intensive, requires trained personnel, and can miss low-abundance biomarkers.
Other traditional methods include chemical assays and ensymatic analysis, which measure specific substances (e.g., creatinine, urea, or albumin). These may provide more accuracy than dipsticks, but they require complex preparation, specialised reagents, and a laboratory infrastructure, resulting in increased time and effort.
Emergence of spectral techniques
Raman spectroscopy is a technique that detects inelastic scattering of monochromatic light. This remarkable sensitivity allows us to identify even trace substances, making it invaluable for applications such as drug detection, doping in sports, and even monitoring therapeutic agents in patients. Its potential is vast, and we're just beginning to scratch the surface of what it can achieve in clinical settings.
FTIR (Fourier Transform Infrared Spectroscopy) is another potentially powerful tool in the diagnostic arsenal. It provides high-resolution spectral fingerprints for urine analysis, which can be critical in distinguishing protein profiles. This is an essential factor when assessing the risk of organ rejection post-transplant. By analysing these profiles, we can gain deeper insights into a patient’s immunological status, guiding more tailored treatment strategies.
Then we have Visible (VIS) and Near-Infrared (NIR) Spectrometry, which employs broad-spectrum light to evaluate a variety of biomarkers. These methods allow us to assess renal function, metabolic health, and detect infections or inflammatory conditions. They play a crucial role in diagnosing kidney stones by examining urine crystallisation and saturation levels.
Fluorescence Spectrometry is equally exciting. This technique measures the emissions from substances that absorb energy, enabling the detection of key fluorophores such as NADH, FAD, and tryptophan. Abnormal levels of these indicators can signal significant metabolic or neoplastic changes, providing vital information for early diagnosis and treatment.
Lastly, the integration of Complementary Sensing-Conductimetry elevates our diagnostic capabilities. By combining traditional conductimetry, an approach that assesses electrical conductivity to gauge total ion concentration, with spectral methods, we enhance overall diagnostic accuracy. This dual approach effectively reduces the chances of false negatives, ensuring that the results we obtain are both reliable and actionable.
The future of diagnostics
The advancement of these spectral techniques for urine analysis is opening doors for rapid and accurate diagnosis. As we continue to explore the potential of liquid biopsies and refine these advanced, non-invasive techniques, we move closer to a healthcare model that not only prioritises early detection but also supports medical professionals in making informed choices for the most appropriate patient care. Although we are still in the early stages, the implications for diagnostics and patient outcomes are profound.
Gaetano Panagia brings a wealth of expertise to Hamamatsu Photonics as a technical marketing engineer. He joined the company in 2021 and specialises in gas sensing, agriphotonics, and food sorting applications, curating technical content and conducting market research on Mid-IR detectors and spectrometers. He is also involved in Hamamatsu’s Pilot Line service, helping customers to design, build, and mass-produce custom optoelectronic modules.
