From the Guidelines
Foam in urine is often a sign of excess protein (proteinuria) and may indicate kidney problems, so if you notice persistent foam in your urine for more than a week, you should consult a healthcare provider for evaluation. This is because proteinuria can be a surrogate marker of the progression of glomerular disease, and the duration and severity of proteinuria are known to predict the prognosis in all histologic variants of idiopathic nephrotic syndrome (INS) 1. The main factor predicting the prognosis in all the histologic variants of INS is the response of proteinuria to therapy, and the objectives of treatment are to lower proteinuria, reduce the frequency of relapses of nephrotic syndrome, and protect the kidney and prevent progression to renal failure 1.
Some common causes of foamy urine include:
- Dehydration
- Rapid urination
- Toilet cleaning chemicals
- Certain medications
- Medical conditions like diabetes, high blood pressure, or kidney disease Proteinuria occurs when damaged kidney filters allow proteins like albumin to pass into urine instead of being retained in the bloodstream 1.
According to the KDIGO practice guideline on glomerulonephritis, initial therapy should be started only in patients with nephrotic syndrome and when at least one of the following conditions is met: urinary protein excretion persistently exceeds 4 g/day, the presence of severe, disabling, or life-threatening symptoms related to the nephrotic syndrome, or the SCr level has risen by 30% or more within 6 to 12 months from the time of diagnosis 1.
In terms of treatment, reduction of proteinuria to less than 1 g/day is associated with a more favorable prognosis, and the use of ACEi or ARB has been associated with proteinuria reduction and a reduction in GFR decline in patients with proteinuria greater than 1 g/day 1. While waiting for a healthcare provider's evaluation, it is essential to stay well-hydrated but avoid excessive fluid intake right before providing a urine sample, as this could dilute results. Occasional foamy urine isn't usually concerning, especially after vigorous exercise or with mild dehydration, but persistent foam warrants medical attention to rule out underlying health issues.
From the Research
Foam in Urine
- Foam in urine is widely regarded as a sign of proteinuria, which is the presence of excess proteins in the urine 2
- A study found that approximately 20% of patients who complained of foamy urine had overt proteinuria, and increased serum creatinine and phosphate were statistically significant risk factors 2
- Proteinuria appears to be an important risk factor for renal function deterioration and for cardiovascular mortality 3
- ACE inhibitors have been shown to reduce proteinuria more effectively than other antihypertensives, and their antiproteinuric effect seems to be independent of the underlying renal disease 3, 4
- The effects of ACE inhibitors on proteinuria are not only due to blood pressure lowering, but also due to efferent (postglomerular) vasodilation 4
- Urine sediment examination remains a useful test for providing information about the patient's underlying kidney disease, and can alert health care providers to the presence of kidney disease 5
- ACEIs and ARBs have been shown to be similarly effective in reducing urinary protein excretion, and can improve blood pressure and reduce urine protein levels 6