Protein in Urine (Proteinuria)

People with proteinuria have urine with an abnormal amount of protein. The condition is often a sign of kidney disease.

Healthy kidneys do not allow a significant amount of protein to pass through their filters. But filters damaged by kidney disease may let proteins such as albumin leak from the blood into the urine.

Proteinuria can also be a result of overproduction of proteins by the body.

Kidney disease often has no early symptoms. One of its first signs may be proteinuria that's discovered by a urine test done during a routine physical exam.

Risk Factors for Proteinuria

The two most common risk factors for proteinuria are:

• Diabetes
• High blood pressure (hypertension)

Both diabetes and high blood pressure can cause damage to the kidneys, which leads to proteinuria.

Other types of kidney disease unrelated to diabetes or high blood pressure can also cause protein to leak into the urine. Examples of other causes include:

• Medications
• Trauma
• Toxins
• Infections
• Immune system disorders

Increased production of proteins in the body can lead to proteinuria. Examples include multiple myeloma and amyloidosis.

Other risk factors include:

• Obesity
• Age over  65
• Family history of kidney disease
• Preeclampsia (high blood pressure and proteinuria in pregnancy)
• Race and ethnicity: African-Americans, Native Americans, Hispanics, and Pacific Islanders are more likely than whites to have high blood pressure and develop kidney disease and proteinuria.

Some people get more protein into urine while standing than while lying down. That is known as orthostatic proteinuria.

Treatment of Proteinuria

Proteinuria is not a specific disease. So its treatment depends on identifying and managing its underlying cause. If that cause is kidney disease, appropriate medical management is essential.

Untreated chronic kidney disease can lead to kidney failure.

In mild or temporary proteinuria, no treatment may be necessary.

Drugs are sometimes prescribed, especially in people with diabetes and/or high blood pressure. These may come from two classes of drugs:

• ACE inhibitors (angiotensin-converting enzyme inhibitors)
• ARBs (angiotensin receptor blockers)

Proper treatment -- especially in patients with chronic disease such as diabetes and high blood pressure -- is essential to prevent the progressive kidney damage that is causing the proteinuria.