Nephrotic syndrome is quite rare but has an important role to play in the development of kidney disease. In adults, the incidence of the condition is approximately 3 cases per 100,000 per year. The incidence of minimal change disease in Caucasian children is reported to be 2 per 100,000.
Individuals of any age can be affected by nephrotic syndrome. However, it primarily affects adults with an adult to child ratio or 26:1. The condition is more common in women than in men with a ratio of 2:1.
Higher rates of nephrotic syndrome have been reported in children of Arabian and Asian racial origins, in contrast to Caucasian children.
The most common cause of nephrotic syndrome in children is minimal change disease. This accounts for up to 90% of cases involved children less than five years old. Minimal change disease can also be responsible for causing the condition in adults, although it is a less prominent cause associated with approximately 1 in 5 cases. Other common causes in children are segmental glomerulosclerosis and mesangiocapillary glomerulonephritis, accounting for approximately 8% and 6% of cases, respectively.
The most common cause of nephrotic syndrome in adults is mesangiocapillary glomerulonephritis, which is responsible for about a third of cases. Other prominent causes include focal and segmental glomerulosclerosis and minimal change disease, each accounting for approximately 20% of cases. In contrast to minimal change disease occuring in children, it usually occurs secondary to another condition, such as diabetic nephropathy.
Spontaneous remission occurs in approximately one-quarter of all cases within the first twelve months of the initiation of symptoms. However, some of these cases will later go on to develop complications, such as chronic renal failure, several years after the remission has been reached. Between 10% and 20% of cases experience a repeated cycle of remissions and relapses, although they do not experience serious complications related to the syndrome.
The main causes of death for patients with nephrotic syndrome are linked to cardiovascular disease, due to the long-term effects on the blood. In particular, hypoalbuminemia, hypercholesterolemia, and hypertriglyceridemia may have an impact on this. Additionally, infections and thromboembolic accidents are also more common causes of mortality in patients with nephrotic syndrome.
There is generally a good prognosis associated with nephrotic syndrome when patients receive appropriate treatment. The actual outcomes depend on the patient characteristics, such as age and gender, underlying cause and the response to treatment.
Minimal change disease, the most common cause in children, has a good response to steroid medication and therefore the prognosis is usually good and rarely results in chronic renal failure.
For patients with nephrotic syndrome caused by mesangiocapillary glomerulonephritis, the prognosis is poorer and kidney failure usually occurs within three years of the development of symptoms. Patients henceforth require dialysis and eventually a kidney transplant.
Without treatment, nephrotic syndrome does not have a good prognosis and usually leads to acute kidney failure. This can occur within a matter of months for rapidly progressing glomerulonephritis.