What Does Protein in Your Urine Mean?

Protein in the urine or proteinuria can be caused by a variety of conditions including kidney disease.

The kidneys function to remove waste and excess water and salts from the blood. Small groups of blood vessels called glomeruli filter the blood, removing these waste products and preventing proteins and other substances from being removed from the blood. If the glomeruli are damaged, protein from the blood can leak into the urine, resulting in high protein levels in the urine (called proteinuria).

Less than 150 milligrams (about 3% of a teaspoon) of protein in the urine per day is normal. More than 150 milligrams of protein in the urine per day is considered proteinuria.

Protein in the urine (proteinuria) is itself a symptom of another condition and there may be no signs. When signs of protein in the urine do occur, they may include: 

• Swelling (edema) in the face, legs, feet, or abdomen 
• Foamy, frothy or bubbly-looking urine 

Protein in the urine can be caused by many things, from dehydration to kidney disease.

There are three types of proteinuria: 

• Transient (intermittent/temporary)
  • Most common form, may be caused by:
  • Fever 
  • Heavy exercise
  • Dehydration
  • Inflammation
  • High levels of stress
  • Very low temperatures
• Orthostatic (related to sitting/standing or lying down)
  • Loss of protein in the urine occurs while in an upright position but not when lying down
  • Cause is unknown
• Persistent (always present)
  • Occurs in people with underlying medical conditions, such as: 
    • Kidney diseases and conditions
    • Urinary tract infections (UTIs)
    • Reflux nephropathy
    • Glomerulonephritis
    • Minimal change nephropathy
    • Kidney stones
  • Diseases that can affect the kidneys
    • Diabetes mellitus 
    • High blood pressure (hypertension)
  • Diseases that cause the body to overproduce certain types of protein

Risk factors for developing protein in the urine include:

• Obesity
• Age over 65
• Family history of kidney disease
• Ethnicity: African American, Native American, Hispanic, or Pacific Islander are at higher risk

Protein in the urine (proteinuria) is diagnosed with:

• Urinalysis
  • Single urine sample collected at any time 
  • 24-hour urine collection
• Blood tests 
  • Kidney function testing, including blood urea nitrogen (BUN) and creatinine 
• Imaging tests
  • Computerized tomography (CT) scan 
  • Ultrasound
• Kidney biopsy 

There is no treatment needed for transient and orthostatic proteinuria as they are not considered harmful conditions. 

Treatment for persistent protein in the urine (proteinuria) involves treating the underlying condition, and may include: 

• Antihypertensive drugs such as angiotensin-converting enzyme (ACE) inhibitors, to reduce or eliminate proteinuria
• Angiotensin receptor blockers (ARBs)
• Treating underlying kidney disease
• Treating and managing diabetes or high blood pressure