What is proteinuria?

Proteinuria is increased levels of protein in the urine. This condition can be a sign of kidney damage.

Proteins – which help build muscle and bone, regulate the amount of fluid in blood, combat infection and repair tissue – should remain in the blood. If proteins enter the urine they ultimately leave the body, which isn’t healthy.

How does protein get into urine?

Protein gets into the urine if the kidneys aren’t working properly. Normally, glomeruli, which are tiny loops of capillaries (blood vessels) in the kidneys, filter waste products and excess water from the blood.

Glomeruli pass these substances, but not larger proteins and blood cells, into the urine. If smaller proteins sneak through the glomeruli, tubules (long, thin, hollow tubes in the kidneys) recapture those proteins and keep them in the body.

However, if the glomeruli or tubules are damaged, if there is a problem with the reabsorption process of the proteins, or if there is an excessive protein load, the proteins will flow into the urine.

How common is proteinuria?

Normal amount of protein in the urine are less than 150mg/day. High levels of protein in the urine are associated with rapid decline in kidney function. It affects about 6.7 percent of the United States population. It is seen more in elderly and people with other chronic illnesses.

What causes proteinuria?

In many cases, proteinuria is caused by relatively benign (non-cancerous) or temporary medical conditions.

These include dehydration, inflammation and low blood pressure. Intense exercise or activity, emotional stress, aspirin therapy and exposure to cold can also trigger proteinuria. In addition, a kidney stone in the urinary tract can cause proteinuria.

Occasionally, proteinuria is an early indication of chronic kidney disease, a gradual loss of kidney function that may eventually require dialysis or a kidney transplant. Diabetes and high-blood pressure can damage kidneys and are the number-one and number-two causes of kidney disease.

Other potentially kidney-harming diseases and medical conditions, which can lead to proteinuria, include:

  • Immune disorders like lupus and Goodpasture’s syndrome
  • Acute inflammation of the kidney (glomerulonephritis)
  • Cancer of plasma cells (multiple myeloma)
  • Intravascular hemolysis, which is the destruction of red blood cells and release of hemoglobin in the bloodstream
  • Cardiovascular disease
  • Preeclampsia, the simultaneous development of hypertension and proteinuria in a pregnant woman
  • Poisoning
  • Trauma
  • Kidney cancer
  • Congestive heart failure

Also, most serious illnesses can result in proteinuria.

What are the symptoms of proteinuria?

Often, someone with proteinuria doesn’t experience symptoms, especially if kidneys are just beginning to have problems. However, if proteinuria is advanced, symptoms can include:

These are also symptoms of chronic kidney disease. Anyone experiencing these symptoms, especially foamy urine and swelling, should see a doctor immediately.

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