Nephrotic syndrome

Nephrotic syndrome: description

A nephrotic syndrome does not describe an independent disease. Rather, the term for the common occurrence of certain symptoms and complaints, the cause of which is a malfunction of the kidneys. Characteristic of a nephrotic syndrome is a pathological loss of protein via the urine (proteinuria). This loss of protein then results in further symptoms such as water retention in the tissue and an increase in blood lipid levels. A nephrotic syndrome can affect both children and adults.

Nephrotic syndrome: symptoms

A nephrotic syndrome causes characteristic symptoms. They can be attributed in particular to the loss of important proteins. Typically, a nephrotic syndrome is associated with the following symptoms:

• Protein in the urine (proteinuria): People often notice that their urine foams heavily.
• Water retention in the tissue (edema): A nephrotic syndrome causes especially edema on the face (especially in the eyelids) and on the feet, ankles and lower legs.
• Protein deficiency in the blood (hypoproteinemia)
• Increased blood lipid levels
• High blood pressure (hypertension)
• Increased susceptibility to infection: About the damaged kidneys, the body also loses antibodies.
• Formation of blood clots (thrombosis): The protein loss causes disorders of the coagulation system. This may make it easier to form a blood clot.

The symptoms that cause a nephrotic syndrome can be individually variable. Some sufferers, therefore, have little discomfort, while others quickly develop the full picture of the syndrome.

Nephrotic syndrome: causes and risk factors

The cause of a nephrotic syndrome is damage to the kidneys. Doctors distinguish whether the disease originates from the kidneys themselves (primary kidney disease) or has developed as a result of another, initially non-kidney disease. You then speak of a secondary kidney disease.

Kidneys as filter systems

The kidneys have the function in the body to filter the blood and to cleanse it of waste products of the metabolism – so-called urinary substances. Larger components such as proteins or sugar molecules normally keep healthy kidneys back, meaning that such substances remain in the blood. The kidneys also regulate blood pressure by controlling the water balance and ensuring that the blood salts (electrolytes) are in the right proportion.

The kidneys ensure their filtering function by means of their special anatomical structure: Kidney bodies (Glumerolum) and renal tubules (Tubulus) together form the nephrone, the smallest functional unit of the organ.

Disturbed filter function

A nephrotic syndrome is due to damage to the kidney bodies (glomerulopathy). These become more permeable, their “filter pores” on – until they finally can no longer fulfill their filter function. It will then lose many important blood components (especially proteins), which are normally withheld. As a result, a nephrotic syndrome develops.

Nephrotic syndrome: causes in adults

A nephrotic syndrome is commonly caused in adults by:

• Chronic inflammatory diseases of the renal corpuscles: These include the so-called membranous glomerulopathy, in which mass antibodies accumulate in the kidney corpuscles. A nephrotic syndrome in adults is usually caused by this condition.
• Diabetes (diabetes mellitus): In particular, deposits that form in the course of diabetes in the renal corpuscles disturb the filter function of the kidneys. Over time, especially with untreated or poorly controlled diabetes, the damage can become so great that a nephrotic syndrome develops.
• Glomerular Minimal Lesions (Minimal Change Glomerulopathy): Disruption of certain immune cells (T cells) causes damage to the renal corpuscles. This condition is responsible for nephrotic syndrome in about ten percent of adults.

Rarer causes of nephrotic syndrome in adults are certain autoimmune diseases (such as systemic lupus erythematosus) and, in the elderly, so-called amyloidosis, in which disease-related protein deposits form in the organs.

Nephrotic syndrome: causes in children

Minimal change glomerulopathy (minimal change glomerulonephritis) is the most common cause of nephrotic syndrome in children.

Nephrotic syndrome: examinations and diagnosis

A nephrotic syndrome usually causes typical symptoms that already provide important clues for the diagnosis. In some cases, a suspected diagnosis is also accidentally produced, for example if the high protein content is noticeable during a urinalysis. For the Urinalysis As a rule, simple test strips are used, which are dipped into the urine for a few minutes.

If the urine contains abnormally large amounts of protein, further investigations are underway. So often a second, more accurate protein determination, this time from a urine sample collected over 24 hours. A healthy person does not excrete more than 150 mg of protein per day; If there is a nephrotic syndrome, the levels may be 3500 mg per day or more.

For further diagnostics are also blood tests necessary. If the doctor has diagnosed a nephrotic syndrome, there is usually one Tissue sample (biopsy) required from the kidney to narrow the exact cause of the disease. As part of a surgical procedure, the doctor removes a small piece of kidney tissue, which is then examined in a histological examination.

Nephrotic syndrome: treatment

A nephrotic syndrome is generally treated according to the underlying condition. However, as these can not always be treated as causally, the therapeutic measures often focus on alleviating the symptoms:

A nephrotic syndrome often goes with it high blood pressure associated. In order to normalize this and to reduce the strong loss of protein, doctors usually use antihypertensive drugs (such as ACE inhibitors). Lowering blood pressure is particularly important, as permanently elevated blood pressure damages the kidneys even more.

The formation of edema is typical of a nephrotic syndrome. As a rule, the accumulations of water can be well washed out with dehydrating agents, so-called diuretics. To prevent fluid from re-accumulating in the tissue, the physician also sets a limit on the daily amount of drink and saline intake (maximum six grams per day). Since the diuretics not only water, but also increasingly electrolytes (such as sodium, potassium) are excreted, the doctor regularly checks the content of mineral salts in the blood. The drainage must not be too sudden, otherwise the body loses too much fluid in a short time. This increases the risk of blood clots.

A nephrotic syndrome is associated with an increased risk of blood clots (Risk of thrombosis), To prevent thrombosis, sufferers receive drugs that inhibit blood clotting (such as low molecular weight heparin). Wearing compression stockings additionally protects against the formation of blood clots. If a thrombosis has already developed, the doctor administers so-called blood thinners – usually they come from the drug class of coumarins.

In some cases, a nephrotic syndrome also calls high blood lipid levels out. They too can be treated with medication using cholesterol-lowering drugs (such as CSE inhibitors). In contrast, a diet low in fat and cholesterol usually does not produce a sufficient effect.

A nephrotic syndrome often goes with one Weakening the immune system and increased susceptibility to infection associated. The reason is the increased loss of antibodies (immunoglobulins) via the urine. Bacterial infections can be combated with antibiotics. If the antibody loss is very large, it is possible to replace the missing immunoglobulins in the form of infusions at least partially. However, if protein loss persists, the replaced antibodies will also be lost. In some cases, vaccination may be useful to protect against certain infections such as pneumococci or influenza (“true” flu).

Treatment of causes

In the case of membranous glomerulopathy, which is one of the most common causes of nephrotic syndrome in adults, a malfunction of the immune system is the trigger. Medicines that suppress the defense and inhibit inflammatory reactions (so-called immunosuppressants) are used here.

In children, minimal change glomerulopathy is the most common cause of nephrotic syndrome. In many cases, the treatment also works well with immunosuppressants such as cortisone. If the drug is discontinued, however, in half of the affected children relapse (recurrence). Then, doctors may use other remedies (such as Ciclosporin A).

Nephrotic syndrome: disease course and prognosis

The nature of the nephrotic syndrome depends primarily on the triggering underlying disease. If treated well, the symptoms of nephrotic syndrome usually disappear after some time.

In many cases, the detoxification function of the kidneys is retained. Are the kidneys through one nephrotic syndrome but severely damaged, chronic renal failure or kidney failure may develop over time.