The Early Warning Sign of Kidney Trouble That Most People Ignore, According to a Nephrologist

The Early Warning Sign of Kidney Trouble That Most People Ignore, According to a NephrologistTaking care of your kidneys is one of the most important things you can do for long-term health. The kidneys act as the body's vital filtration system, removing waste and excess fluid from the blood while helping essential processes like blood pressure regulation. When kidney function declines, waste products and extra fluid build up in the bloodstream, leading to serious health complications.

Factors like high blood pressure, uncontrolled diabetes, and excessive use of pain medications can contribute to kidney damage over time. Kidney disease is also often a silent condition, with noticeable symptoms not appearing until the disease has progressed and is irreversible. You might, however, notice subtle changes, and one nephrologist points to a seemingly innocent bathroom observation as an early warning sign of potential trouble.

"Significantly foamy urine can be a sign of high levels of protein in the urine," says John Sperati, MD, MHS, nephrologist and professor of clinical medicine at the Johns Hopkins University School of Medicine. "In particular, bubbles that remain in the toilet after flushing may be more likely to be due to health issues rather than innocent causes such as substances in food that we eat and drink or cleaning chemicals in the toilet."

In normal health, urine contains very small to minimal amounts of protein because healthy kidneys keep most proteins in the bloodstream rather than allowing them to pass into the urine. In some forms of kidney disease, however, large amounts of protein are lost from the blood into the urine. This can sometimes make urine appear unusually foamy or bubbly. Particularly, this is more common with a certain type of kidney disease, known as glomerular disease.

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Keep in mind, foamy or bubbly urine might also be completely normal. To rule out kidney issues, take a simple urine test to determine if elevated levels of protein are present or not. If there's concern for kidney disease, your doctor might start with a measurement of the urine albumin to creatinine ratio (UACR) and blood creatinine to calculate estimated glomerular filtration rate (eGFR). The National Kidney Foundation encourages you to Know Your Kidney Numbers.

"Kidney disease might not have any symptoms. Most importantly, if you have a family history of kidney disease or if you have diabetes mellitus, high blood pressure, or obesity, speak with your doctor to ensure you're being appropriately screened for the presence of kidney disease as part of routine healthcare," Sperati says.

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John Sperati, MD, MHS, nephrologist and professor of clinical medicine at the Johns Hopkins University School of Medicine

This story was originally published by Men's Journal on Oct 8, 2026, where it first appeared in the Health section. Add Men's Journal as a Preferred Source by clicking here.