Nephrotic syndrome


What is nephrotic syndrome?
Nephrotic syndrome is a common manifestation of glomerular disease, caused by a variety of etiologies, with large differences in treatment response and prognosis. The pathological causes of nephrotic syndrome are diverse, with the most common types being minimal change disease, focal segmental glomerulosclerosis, mesangial proliferative nephritis, membranous nephropathy, and membranoproliferative glomerulonephritis. Nephrotic syndrome can be classified into primary and secondary types based on its cause. The diagnosis of primary nephrotic syndrome mainly depends on the exclusion of secondary nephrotic syndrome. Common causes of secondary nephrotic syndrome include diabetic nephropathy, lupus nephritis, renal amyloidosis, drug-induced nephropathy, and renal tumors.


Criteria for the diagnosis of nephrotic syndrome
The diagnostic criteria for nephrotic syndrome include massive proteinuria, with urinary protein greater than 3.5 grams/day, hypoalbuminemia, with plasma albumin less than 30 grams/liter, severe edema, and hyperlipidemia, which includes significant increases in plasma cholesterol and triglycerides. The first two criteria are essential for the diagnosis of nephrotic syndrome, while the latter two are secondary. Clinically, if the two necessary criteria are met, the diagnosis of nephrotic syndrome is established. Patients with nephrotic syndrome should undergo a renal biopsy to determine the pathological type and guide clinical treatment.


Does nephrotic syndrome require a puncture?
Nephrotic syndrome is a complex of clinical symptoms with various causes, which differ by age group. In children or adolescents, if it presents solely as significant proteinuria without elevated creatinine or hematuria, it is generally caused by minimal change disease. Since this type of kidney disease is sensitive to hormone treatment, it is usually possible to forego renal biopsy and start with corticosteroid therapy. For other nephrotic syndrome patients, it is advisable to first perform a renal biopsy to identify the pathological cause before considering appropriate treatment with hormones, immunosuppressants, and other medications.


What to do if nephrotic syndrome causes leg pain?
Patients with nephrotic syndrome who experience leg pain mostly have conditions unrelated to nephrotic syndrome itself. It could be due to diseases of the skeletal or muscular system. However, some patients might experience leg pain due to thrombosis caused by nephrotic syndrome, leading to ischemia in the limbs. Also, long-term use of corticosteroids can lead to necrosis of the femoral head, osteoporosis, and pain. Therefore, treatment should be targeted based on the cause, such as using drugs to dissolve clots or interventional surgery for those with thrombosis. In severe cases of femoral head necrosis, a femoral head replacement surgery might be necessary, and it is important to supplement with calcium regularly.


Characteristics of Nephrotic Syndrome
The characteristics of nephrotic syndrome are defined by significant proteinuria, where significant proteinuria refers to urinary protein exceeding 3.5 grams in 24 hours; hypoproteinemia, which refers to blood albumin levels below 30 grams per liter; edema, which may present in facial and lower limbs, and even severe patients may exhibit generalized edema around both lower limbs; and hyperlipidemia, characterized by increased cholesterol and triglycerides in the blood. These patients may exhibit reduced urine output, edema, and noticeably increased foam in the urine.


What tests are conducted for nephrotic syndrome?
Patients with nephrotic syndrome need to complete routine urine tests, 24-hour urine protein quantification, liver and kidney function tests, routine blood tests, electrolyte panels, blood glucose tests, and lipid profiles. Additionally, it is important to determine the cause of nephrotic syndrome, excluding the possibility of nephrotic syndrome caused by immune system diseases, including tumors, vasculitis, lupus, and other diseases. These tests include rheumatoid immune panels, antinuclear antibody spectrum, anti-GBM antibodies, ANCA panel, and immunoglobulins. Moreover, these patients should undergo kidney ultrasound, tumor marker tests, and thyroid function tests.


Characteristics of Nephrotic Syndrome
The characteristic feature of nephrotic syndrome is that patients may experience edema, which is related to the nature of this disease. The essence of this disease is due to some reason that damages the glomerular capillary filtration barrier. As a result, when blood passes through the glomeruli, it leaks proteins from the blood. A 24-hour urinary protein quantification will exceed 3.5 grams, which constitutes a large amount of urinary protein. Consequently, a large amount of protein is leaked into the urine, causing the protein concentration in the plasma to decrease. This leads to a reduction in the colloidal osmotic pressure of the plasma, causing fluid to move from inside the blood vessels to outside, thus leading to edema. Therefore, the most significant clinical feature of nephrotic syndrome is the potential to cause edema, and severe cases of edema may elevate blood pressure, lead to pulmonary edema, manifesting as difficulty breathing, chest tightness, and shortness of breath.


Is nephrotic syndrome prone to recurrence?
Nephrotic syndrome is characterized by more than 3.5 grams of proteinuria in 24 hours and a serum albumin concentration lower than 30 grams per liter. Treatment of this disease should be aimed at the cause, with most patients suffering from primary nephrotic syndrome related to immune dysfunction, therefore often requiring treatment with steroids. Indeed, some patients easily experience relapses; after a period of steroid treatment, proteinuria may decrease or even turn negative. However, upon cessation of the medication or during occurrences like a cold, some patients may suffer from relapses. Not all patients respond this way, as some are dependent on steroids.


Is nephrotic syndrome contagious?
So, nephrotic syndrome is a general term for a group of clinical symptoms, a state of disease, and is not essentially an independent disease. Thus, this problem is not infectious. This disease describes the damage to the kidneys due to some reason, leading to the disruption of the integrity of the glomerular filtration barrier, resulting in the patient developing a significant amount of urinary protein. The disease itself is not contagious. However, there are very few cases of nephrotic syndrome that might be caused by hepatitis B virus infecting the kidneys. In such cases, the hepatitis B virus may have a certain level of contagiousness, but even so, it does not imply that nephrotic syndrome itself is contagious. In other words, even if such patients transmit hepatitis B to others, it does not necessarily mean those others will exhibit kidney damage.


Can nephrotic syndrome be clinically cured?
Nephrotic syndrome, a disease that clinically cannot be completely cured, is a chronic illness with no concept of cure. However, with appropriate treatment plans, many patients can achieve effective relief. There are two criteria for judging treatment effectiveness: first, the patient's 24-hour urinary protein quantification is controlled below 0.5 grams, and even can be controlled below 0.3 grams. Second, the patient's 24-hour urinary protein quantification is reduced by more than half compared to the baseline value. Both scenarios indicate effective treatment, but achieving a complete cure is difficult.