Normal people will occasionally have foam in their urine, and most will gradually dissipate in less than half an hour. The foam at this time is mainly caused by the concentration of urine, the increase of inorganic salt components in urine, and the rise of tension. The foam at this time is generally larger foam, and the greater the urinary drop, the more foam appears. This condition usually occurs in the morning when you urinate for the first time, or when you drink less water and sweat more. In contrast, the foam caused by elevated urine protein due to nephritis is usually small, delicate foam, like beer foam, that lasts for a very long time, and some patients can last for several hours before dissipating. Other diseases such as diabetes mellitus also cause foam due to elevated glucose in the urine. To identify whether the elevated foam in the urine is caused by a disease or by a physiological condition, a routine urine test is required, preferably done with morning urine, which has a higher probability of being positive.