How the power of smell could identify new medical tests

Since ancient times, physicians have noticed a sweet smell in the urine and breath of people with diabetes. Failures of the liver or kidneys also alter the breath with fish-like and urine-like smells, respectively. These smells come from changes in the usual biochemical processes in the body, producing a variety of metabolites known as volatile organic compounds (VOCs) that disperse into the air.

While blood tests and imaging scans have become mainstays of modern medicine, the compounds that we release into the air around us have gone largely unnoticed. The advances in technology have made it worth investigating smell because it is easier to detect compounds at lower concentrations.