Foamy Urine, Proteinuria and Renal Function Damage

Proteinuria is one of the common symptoms of the disease of Polycystic Kidney Disease (PKD). And in many cases, proteinuria manifests as foamy urine. Therefore, when somebody found there is foam in the urine, they usually doubt they have kidney disease and their renal function damage has taken place. While the facts are not as people think.

First, Foamy urine does not always mean proteinuria: under normal circumstance, fresh urine is clear and flaxen. The surface tension of the urine is rather low, so there are rarely bubbles in the urine. If the normal contains some organic substance (such as glucose) and inorganic substance (such as mineral salt), it may strengthen the surface tension of the urine and then there may be some foam in the urine cause by the impact force of pee. In this case, these foams are not in uniform size and they usually disappear soon. Therefore, foamy urine does not mean proteinuria.

Second, proteinurina does not always mean the kidney disease: just as its name implies, proteinuria means that there is protein in the urine. There is a little protein in the urine of healthy people, while the amount of protein in the 24 hour’s urine will not surpass 0.15g. Common clinical test can’t detect these trace of protein, and the test report shows that the urine protein is negative. If the amount of the protein in the urine increases, the surface tension of the urine will increase and there may be some foams when people urinate. However, even if people have found protein in the urine, it does not certainly mean kidney disease. Sometimes, in some particular cases, such as in cold seasons, having a high fever, serious pain, emotional stress, strenuous exercise, taking in too much protein and being poisoning, people can also be detected with protein in the urine.

Third, foamy urine can’t reflect the damaged degree of renal function. To confirm the renal function, people should take renal function test to detect the renal function, instead of just relying on the foamy urine.


In a word, people should not just think things with their eyes. Foamy urine does not certainly mean proteinuria. Otherwise, non-foam urine does not mean people have no proteinuria. There is no certain inevitable relation among foamy urine, proteinuria and renal function damage. People should take relevant medical tests to determine whether they have kidney disease and renal function damage in order to adopt treatment in time.