Long-term nephrotic syndrome can lead to irreparable kidney damage leading to kidney failure, necessitating treatment with dialysis or, eventually, kidney transplant.
The glomeruli act as filters to remove waste products from the blood, which are 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 blood protein levels cause water to leak into body tissue, causing swelling.
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 segmental glomerulonephritis.
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. This form of nephrotic syndrome affects approximately 1 in 50,000 children. It can usually be successfully treated. In adults, membranous glomerulonephritis and focal segmental glomerulonephritis are the most common causes of the nephrotic syndrome.
Signs and symptoms
Signs and symptoms include:
- Foamy urine
- Fatigue and weakness
- Swelling, especially 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 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 anaesthetic or a local anaesthetic. Ultrasound scanning of the kidneys may also be performed.
Medications that reduce the inflammatory effects of the immune system on the glomeruli are the mainstay of treatment. Medications to achieve this include corticosteroids (eg: prednisone) and potent immune-suppressing medications such as cyclosporine, cyclophosphamide, mycophenolate and rituximab. Medications to reduce high blood pressure and high blood cholesterol levels may also be prescribed. Blood thinning medications (anticoagulants) may be prescribed to reduce the risk of developing blood clots.
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 levels of protein, salt and cholesterol 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
Freephone: 0800 543 639
Kidney Health New Zealand (2008). Nephrotic syndrome in children: What is nephrotic syndrome? (Information Sheet). Christchurch: Kidney Health New Zealand. https://www.kidneys.co.nz/resources/file/nephrotic_syndrome_in_children_03.pdf
Mayo Clinic (2014). Nephrotic syndrome (Web Page). Rochester, NY: Mayo Foundation for Medical Education and Research. https://www.mayoclinic.org/diseases-conditions/nephrotic-syndrome/basics/definition/con-20033385 [Accessed: 14/11/17]
O’Toole, M.T. (Ed.) (2013). Nephrotic syndrome. Mosby’s Dictionary of Medicine, Nursing & Health Professions (9th ed.). St Louis, MI: Elsevier Mosby.
Last Reviewed – December 2017