Urine testing over time

Blood, phlegm, yellow bile, and black bile were the scaffold of Hippocrates’ theory of the four humors. Like many of his contemporaries, Hippocrates believed that disease was the result of an imbalance between these four bodily fluids.

The idea that we can draw conclusions about processes happening inside the body by analyzing the fluids we excrete is not new. Stone tablets dating back thousands of years show that humans in Mesopotamia and Ancient Egypt analyzed waste from the kidneys to find out what was causing an illness. These uroscopists would primarily study the color, cloudiness, taste, and smell of the urine.

A complex spectrum of properties of urine were considered during diagnosis. At the break of dawn, the patient’s highly concentrated morning urine would be collected in a special flask known as a matula. This would be given to the uroscopist, who would immediately analyze the urine and diagnose the patient based on the urine’s consistency, impurities, taste, smell, and color when compared to 20 color samples on a wheel.

As anyone who has ever eaten asparagus or a lot of garlic knows, certain foods can change the way our urine smells and so give clues as to our eating habits at a given moment. The color of our urine can also change when we eat things like berries. 

Medical texts from the Middle Ages, such as those in Ortolf von Baierland’s pharmacopeia from around 1300 AD, provided detailed instructions and diagrams for analyzing urine. As well as examining the urine itself, uroscopists would also study a ring of residue on the surface. A greenish ring meant the patient was becoming insane, while a thick red ring indicated illness in the forehead caused by excessive blood.¹

The color, smell, and look of urine no longer play the important clinical role they once did. Nevertheless, abnormalities in these properties are still documented and can provide initial clues—such as visible fecal impurities that suggest a gastrointestinal fistula, or a pungent smell that could indicate a urinary tract infection.² 

The practice of analyzing urine began earlier than 6000 BC and continues to evolve today. Rapid test strips and complex laboratory tests offer physicians insights into specific components of the urine, such as blood, sugar, protein, nitrites, bacteria, and other pathogens. Thanks to high-quality strips and automated workflows today, results are more reliable as the user bias caused by subjectivity in visual reads can be eliminated. The findings can lead to diagnoses of diabetes, urinary tract infections, and uncover early signs of kidney illness, e.g., nephritis, which can help improve patient outcomes. As our understanding of the organic connections within the body deepens, it could open up more possibilities for this diagnostic method in the future.