Nephrotic Syndrome is a disease in which the kidney leaks too much protein. This occurs predominantly in children but can also affect adults. The disease has an incidence of 2 to 7 per 100,000 and a prevalence of 16 of 100,000 in children. It is one of most common chronic conditions affecting children.
What is Nephrotic Syndrome?
Nephrotic syndrome occurs due to damage to the glomerulus, which is the filtering unit of the kidney. The damaged glomerulus allows leakage of excess protein. This results in a classical triad of nephritic syndrome which comprises:
- Proteinuria: The loss of protein in the urine. In nephritic syndrome, patients excrete more than 3.5g of protein/day.
- Hypoalbuminemia: this is a reduction in the amount of albumin, which a certain type of protein in the body.
- Hyperlipidemia: this is the finding of elevated lipids in the blood. This occurs due to a compensatory increase in proteins that carry lipids to make up for the loss of proteins in the urine.
Causes of Nephrotic Syndrome
- Glomerular diseases
- Minimal Change Disease
- Membranous Glomerulonephritis
- Focal Segmental Glomerulosclerosis
- Diabetes Mellitus
- Systemic Lupus Erythematosus
Symptoms of Nephrotic Syndrome
- Swelling of the body generally starting with facial puffiness spreading to the abdomen, arms, and legs
- Frequent urination
- Passage of frothy urine
Complications of Nephrotic Syndrome
- Infections: The proteins lost in the urine include antibodies which contribute to immunity. Therefore they are at an increased risk for infections.
- Increased risk of blood clots: Some proteins responsible for preventing blood clots are also lost which can increase the risk of clot formation in the veins.
- Peritonitis: The excess fluid in the abdomen can get infected and inflamed leading to peritonitis.
- End-stage kidney disease and kidney failure: Certain forms of the nephritic syndrome can rapidly worsen leading to loss of kidney function. These patients can die if not provided dialysis and may require a kidney transplant.
Diagnosis of Nephrotic Syndrome
The diagnosis is suspected based on the history of swelling of the body and is confirmed after establishing the presence of protein in the urine. The following tests are performed
- Urine dipstick to instantly screen for protein in the urine
- 24 hour urine collection to test for proteinuria
- Urine routine and microscopy to look for blood and fat calls in the urine
- Kidney function tests to test serum creatinine and blood urea nitrogen
- Serum protein and serum albumin
- Serum lipid levels
- Kidney Biopsy: In rare cases of nephrotic syndrome, which do not resolve with initial treatment, a biopsy may help establish the underlying cause.
Treatment of Nephrotic Syndrome
The management of Nephrotic Syndrome involves treating various components of the disease.
- Proteinuria: This can be controlled using drugs in the category of ACE (Angiotensin-converting enzyme) inhibitors and ARB (Angiotensin receptor blockers). These drugs are effective in controlling the filtering of protein through the glomerulus.
- Swelling: The excess fluid in the body can be induced to pass out in the urine using diuretics like Lasix.
- Hypoalbuminemia: This can be replenished through infusing albumin.
- Disease Activity: The first line to control the disease is the use of steroids like prednisone. Occasionally patients who are not responsive or those requiring steroids for prolonged periods may require alternative immunosuppressive drugs like methotrexate, cyclophosphamide, azathioprine.
Prognosis of Nephrotic Syndrome
The course of the disease varies depending on the underlying cause. In children who predominantly have minimal change disease in the glomerulus, the disease frequently resolves completely and the treatment can be tapered and stopped. In other variations and in adults, a chronic course may be seen with frequent exacerbations and resolutions with dependency on steroids or other immunosuppressive drugs.