A digital sensing platform that runs on a smartphone camera and a battery-powered laser diode could allow patients with chronic kidney ailments or diabetes to test their own urine albumin levels and transmit the data to the doctor or lab.
What is the main focus of this research and technology?
Dr. Ozcan: To enable frequent and routine urine testing, we demonstrated a smartphone-based digital sensing platform called the Albumin Tester, which can measure and quantify the albumin concentration in urine samples through the use of a sensitive and specific fluorescent assay performed in disposable test tubes.
Using a simple sample preparation approach, which takes approximately five minutes per test (including the incubation time), we experimentally confirmed the detection limit of our sensing platform as 5-10 μg/mL. That is more than three times lower than clinically accepted normal range.
This automated albumin-testing tool running on a smartphone could be useful for early diagnosis of kidney disease or for monitoring/management of chronic patients, especially those suffering from diabetes, hypertension, and/or cardiovascular diseases.
What motivated you and your team to develop the Albumin Tester?
Dr. Ozcan: Chronic kidney disease has become a major health issue worldwide, causing millions of deaths every year. Microalbuminuria testing is typically employed as an initial screening tool for kidney disease. Albumin should not exist in urine at more than a clinically normal threshold value of 30 μg/mL. Persons with microalbuminuria typically exhibit albumin levels greater than 30-300 μg/mL in urine.
What are the limitations of the current methods of albumin testing?
Dr. Ozcan: Early stages of kidney disease can be diagnosed using various tests performed on, for example, blood pressure, serum creatinine, and urine albumin. In fact, albumin testing is now routinely ordered within a typical panel of standard lab tests performed in urine for general health screening.
Because the albumin levels in blood and urine fluctuate based on various factors such as metabolism and dietary variations of the patient, timed urine collection or testing methods should be performed every few hours to provide reliable estimates for urinary albumin concentration.
These repetitive clinical measurements are typically achieved through the use of bulky and costly benchtop urine analyzers, limiting the testing and diagnosis of microalbuminuria to laboratory settings, which also requires successive patient visits to central clinics or hospitals.
By designing an integrated measurement and analysis system on a smartphone, we created a compact, lightweight, and cost-effective device that can accurately, sensitively, and rapidly measure and report urinary albumin and assist diagnosis of microalbuminuria.