Foam in urine

Within certain limits, the occasional presence of foam in the urine is a typical characteristic of this liquid, produced by the filtering activity of the kidney with the aim of eliminating the metabolic waste that circulates in the blood. This feature can be further enhanced by detergent residues on the toilet surfaces.

If present, the foam in the urine should be made up of large bubbles, which quickly disappear; Smaller and more persistent bubbles, similar to those of beer, are instead the indicator of various pathologies affecting, above all, the kidney. Foamy urines are in fact associated with proteinuria (detection of proteins in the urine) which is associated - in turn - with pathologies such as renal and cardiac insufficiency, severe hypertension or diabetes. The renal filtration system can also be damaged by other diseases, such as systemic lupus erythematosus, chronic liver diseases or infectious diseases. Because of these damages, the proteins - normally retained - are poured in varying amounts into the urine, causing the formation of foam. Among all, albumin is the protein fraction that is mostly lost (albuminuria).

The morbid processes responsible for proteinuria are often accompanied also by edema, that is to the accumulation of liquids in the interstitial spaces, following the decrease of the plasma oncotic pressure.

Like proteinuria, the accumulation of bile salts (colaluria) is typically associated with foamy urine (with yellowish foam and dark color). The diseases that can cause cholaluria are those that obstruct the biliary tract, such as gallbladder stones.

Finally, the loss of very small amounts of protein in the urine is common following the excesses of a high-protein diet, a particularly heavy physical activity or during pregnancy.