Mayo Clinic Health Manager
Get free personalized health guidance for you and your family.
Get Started
About our e-newsletters
- Free e-newsletters
- Mayo Clinic expertise
- We do not share your e-mail address
Housecall, our weekly general-interest e-newsletter, keeps you up to date on a wide variety of health topics with timely, reliable, practical information, recipes, blogs, questions and answers with Mayo Clinic experts and more. Our biweekly topic-specific e-newsletters also include blogs, questions and answers with Mayo Clinic experts, and other useful information that will help you manage your health.
Housecall Archives
Mayo Clinic Housecall
Stay up to date on the latest health information.
What you get
- Free weekly e-newsletter
- Mayo Clinic expertise
- Recipes, tools and other helpful information
- We do not share your e-mail address
Causes
By Mayo Clinic staff
Nephrotic syndrome is caused by damage to the tiny blood vessels (glomeruli) of your kidneys.
Your kidneys are two bean-shaped, fist-sized organs situated at the small of your back, just below your rib cage, one on each side of your spine. Blood enters your kidneys through arteries from your aorta, the large artery that carries blood away from your heart. Each kidney contains approximately 1 million glomeruli (the singular word form is glomerulus), each of which is attached to the opening of a small fluid-collecting tube (tubule). Each glomerulus and its tubule form a nephron, the functional unit of the kidneys.
A filtering role
The glomeruli filter your blood as it passes through your kidneys. After being filtered by the glomeruli, blood travels through veins in your kidneys back to your bloodstream. The filtered substances, after being modified by the tubules, go through a tube from each kidney (ureter) to your bladder and pass out of your body when you urinate.
Every day about 2 quarts of water, along with waste products and electrolytes, leave your body as urine. When your kidneys lose their filtering ability, dangerous levels of fluid and waste accumulate in your body, a condition known as kidney failure.
What happens in nephrotic syndrome
Healthy glomeruli keep blood protein (mainly albumin) — which is needed to maintain the right amount of fluid in your body — from seeping into your urine. When damaged, glomeruli often lose this ability. Loss of blood protein leads to nephrotic syndrome, which is characterized by:
- High levels of protein in your urine (proteinuria)
- Low levels of the blood protein albumin (hypoalbuminemia)
- Elevated blood levels of cholesterol and triglycerides
- Swelling (edema)
Many possible causes
Many disorders can cause glomerular damage and lead to nephrotic syndrome. The following medical conditions account for most cases of nephrotic syndrome:
- Minimal change disease. The most common cause of nephrotic syndrome in children, this disorder results in abnormal kidney function, but when the kidney tissue is examined under a light microscope, it appears normal or nearly normal. The cause of the abnormal function typically can't be determined.
- Focal segmental glomerulosclerosis. Characterized by scattered scarring of some of the glomeruli, this condition may result from another disease, a genetic defect or occur for no known reason.
- Membranous nephropathy. This kidney disorder is the result of thickening membranes within the glomeruli. The exact cause of the thickening isn't known, but it's sometimes associated with other medical conditions, such as hepatitis B, malaria, lupus and cancer.
- Diabetic kidney disease. Diabetes can lead to kidney damage (diabetic nephropathy) that affects the glomeruli, particularly in people with diabetes that's poorly controlled or people who have high blood pressure.
- Systemic lupus erythematosus. This chronic inflammatory disease can lead to serious kidney damage.
- Amyloidosis. This disorder occurs when substances called amyloid proteins accumulate in your organs. Amyloid buildup often affects the kidneys, damaging their filtering system.
