What causes urine to foam up really big in the toilet after peeing?

Foamy urine is caused by a number of factors, including speed of urination and urine protein content, according to the Mayo Clinic. Persistently foamy urine that becomes more noticeable over time may be the result of escalated protein content, which could indicate serious kidney problems.

Everyone occasionally produces foamy urine, notes the Mayo Clinic. However, if the urine foams regularly, it may be caused by a condition known as Proteinuria, or the presence of unusually large quantities of protein in the urine, explains the American Kidney Fund. While a very small amount of protein is common, large amounts are a cause for concern. It is important to consult a doctor if urine is consistently foamy.