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Nephrotic syndrome is a kidney disorder characterised by high levels of protein in the urine and swelling of body tissue. People of any age can be affected by nephrotic syndrome, although children aged between 18 months and four years are at increased risk.
Long-term nephrotic syndrome can lead to irreparable damage leading to kidney failure, necessitating treatment with dialysis or, eventually, kidney transplant.
Nephrotic syndrome is a collection of symptoms and signs that occur because tiny blood vessels (the glomeruli) in the kidneys do not function correctly. The syndrome is characterised by abnormally high levels of protein in the urine (proteinuria) and abnormally low protein levels in the blood, as well as high cholesterol levels in some cases together with swelling (oedema).
The glomeruli act as filters to remove waste products from the blood, which is then excreted from the body in the urine. In nephrotic syndrome these filters become defective and leak, allowing large quantities of protein to be lost in the urine.
Protein in the blood acts to prevent water entering the body’s cells. Reduced protein levels means water leaks into body tissue, causing swelling (oedema).
In New Zealand, the most common cause of the nephrotic syndrome is glomerulonephritis - a group of kidney diseases where the glomeruli become inflamed. Malfunction of the immune system is thought to be the underlying cause of glomerulonephritis. For some reason the immune system attacks and damages the glomeruli. The three most common forms of glomerulonephritis causing nephrotic syndrome are:
- Minimal change nephropathy (also called minimal change disease).
- Membranous glomerulonephritis.
- Focal sclerosing glomerulonephritis.
A wide range of other disorders (including diabetes mellitus and lupus) and toxins are less common causes of the nephrotic syndrome.
In children, nephrotic syndrome is normally detected between the age of 3 and 4 years old. The majority of children have the form of glomerulonephritis called minimal change nephropathy. This is where minimal or no glomerular abnormalities are noted by a microscope. It can usually be successfully treated.
In adults, membranous glomerulonephritis and focal sclerosing glomerulonephritis are the most common causes of the nephrotic syndrome.
Signs and Symptons
Signs and symptoms include:
- Foamy urine
- Fatigue and weakness
- Swelling (odema) around the eyes, hands, feet, and abdomen
- Loss of appetite
- Increased weight from fluid retention
- High protein levels in the urine and low protein levels in the blood
As the condition progresses there may be:
- Susceptibility to infectious diseases due to an impaired immune system
- An increased risk of blood clots (thrombosis)
- Muscle wasting (due to the loss of protein)
- Weakening of the bones
- Abnormally low or abnormally high blood pressure
- High blood cholesterol levels
- Kidney failure.
A referral to a nephrologist (kidney specialist) may be required in order for a diagnosis to be made. The doctor will take samples of the blood and urine. If results show large amounts of protein in the urine and decreased amounts of protein in the blood, the doctor may recommend a kidney biopsy.
A kidney biopsy is where a tiny piece of kidney is removed by a needle and studied under a microscope. This procedure usually involves a one-day stay in hospital and is performed under a light general anesthetic or a local anaesthetic. Ultrasound scanning of the kidneys may also be performed.
Treatment will depend on the underlying cause of the condition and is aimed at alleviating symptoms and preventing complications.
Medications that reduce the effect of the immune system on the glomeruli are the mainstay of treatment. Medications to achieve this include steroids (eg: prednisone) and potent medications such as cyclosporine and cyclophosphamide.
Medications to decrease high blood pressure and high blood cholesterol levels may also be prescribed.
The doctor may also recommend restricting fluid intake or may prescribe medications that increase the amount of urine produced (diuretics). These, along with bed rest, will help to reduce swelling.
The doctor or a dietitian may recommend a special diet aimed at controlling the amount of protein and salt in the body. Overall, it is important to maintain good health and nutrition and to ensure other medical conditions are treated promptly.
Further Information and Support
Kidney Health New Zealand (formerly the Kidney Foundation) offers support, information and education about kidney disease. Details about local support groups are available from the national head office. Contact details are:
Kidney Health New Zealand
PO Box 139
Freephone: 0800 543 639
Anderson, K.N., Anderson, L.E. & Glanze, W.D. (eds.) (2006) Mosby’s medical, nursing, & allied health dictionary (6th ed.) St. Louis: Mosby-Year Book, Inc.
Bailey, R.R. Nephrotic syndrome. In T. Speight & J. Sutherland (eds.), New ethicals disease index (4th ed.) Auckland: Adis International Limited
Carson-De Witt, R. (2006) Nephrotic syndrome. The Gale Encyclopedia of Medicine. Third Edition. Jacqueline L. Longe, Editor. Farmington Hills, MI. Thompson Gale.
Whitworth J.A. & Lawrence J.R. (eds.) Textbook of renal disease (2nd ed.) Edinburgh: Churchill Livingstone
Last Reviewed – 05/09/07