Nephrotic syndrome

Definition

The nephrotic syndrome describes a clinical picture that arises due to damage to the kidney. The existing damage results in increased excretion of proteins via urine (at least 3.5g per day). As a result, there are fewer proteins in the blood that can bind water. This leads to water retention in the body. In addition, the level of fats in the blood is increased.

Causes

The nephrotic syndrome can be caused by various diseases of the kidney. There are some diseases that affect the renal corpuscle, the glomerulus. Glomerulus is responsible for filtering water and many other substances that have to be excreted in the urine.

The resulting urine is then transported to the bladder via the ureters. The kidney corpuscles in healthy people only allow very small particles to pass through their filter. However, if they suffer from an inflammation, called glomerulonephritis, the filter can be damaged.

As a result, larger substances such as proteins can now also be excreted. As a result, there is a lack of proteins in the blood. Especially albumin, the most common protein in the blood, is important for binding water.

So if there is a protein deficiency in the blood due to damage to the kidneys, the water can no longer be held in the vessels and water retention occurs. The described loss of function of the renal corpuscles can also be caused by deposits of harmful substances. In diabetes mellitus, too, a sugar level in the blood that is elevated over a long period of time can lead to deposits in the kidney and thus to damage of the filter.

Associated symptoms

Common accompanying symptoms include water retention (edema) and high blood pressure. In addition, the proportion of fats and cholesterol in the blood predominates. Furthermore, urination often results in foamy urine due to the high protein content.

This foam is usually so stable that it not only becomes visible when it hits the water in the toilet and then bursts, but remains lying on the water like a foamy blanket. A protein that is important for inhibiting blood clotting is also lost through urine. It is called antithrombin III and inhibits the binding of blood platelets.

If there is a deficiency of antithrombin III in nephrotic syndrome, the formation of blood clots and thromboses is increased. A further accompanying symptom is increased susceptibility to infectious diseases. This is caused by the loss of antibodies in the blood, which are also proteins.

They are responsible for defending against pathogens and thereby activate the immune system. A lack of antibodies thus reduces the body’s protection against disease. In addition, nephrotic syndrome also results in increased excretion of calcium, as this is normally present in the blood bound to proteins.

The reduced calcium can cause accompanying symptoms of diarrhea, hair and nail changes and even cardiac arrhythmia. Water retention in tissue is called edema. They occur in nephrotic syndrome as a result of a protein deficiency in the blood.

Proteins are also called proteins and are negatively charged molecules that attract water due to their chemical properties. Therefore they are called osmotically active particles. If some of the proteins are missing in the blood, the osmotic pressure is lowered.

As a result, the water can no longer be retained and escapes from the vessels. This leads to water accumulation in the body, which is called protein deficiency edema. One speaks of hypertension from a value of over 140/90mmHg.

The volume of blood in the blood vessels is decisive for blood pressure. You can imagine it like a rubber tube, if more fluid is pressed into it, the pressure inside rises. If a nephrotic syndrome results in such severe damage to the kidneys that little or no water can be excreted, it collects in the body.

As a result, there is more fluid in the blood vessels and an increased blood pressure results. The protein deficiency in the blood caused by the nephrotic syndrome is very dangerous for the body. Therefore, it reproduces many proteins, of which only the larger ones are not excreted and thus accumulate.

These include lipoproteins, for example. They are responsible for binding cholesterol and transporting it in the blood. An increased concentration of lipoproteins therefore also increases the cholesterol level in the blood and leads to hypercholesterolemia.You can find detailed information on this topic at Hypercholisterinaemia