Diagnosis

cholesterol

General

The cholesterol (also Cholesterol, Cholest-5-en-3ß-ol, 5-Cholesten-3ß-ol) is a white, almost odorless solid that occurs in all animal cells.
The term is made up of the Greek “chole” = “bile” and “stereos” = “solid”, as it was found in gallstones as early as the 18th century.

function

Cholesterol is a vital sterol and a very important component of the plasma membrane in cells, as it, together with other proteins, contributes to their stability.

It also serves to transport signal substances into the cells or out of the cells. Since cholesterol is not water-soluble (lipophilic and hydrophobic), it is mainly located in the cells.

The human body contains around 140g of cholesterol. In order to be able to transport this in the blood, the cholesterol is bound to lipoproteins. These are divided into 5 groups according to their different densities:

Chylomicrons,
very low density lipoproteins (VLDL),
intermediate density lipoproteins (IDL),
low density lipoproteins (LDL) and
high density lipoproteins (HDL).

In the body, cholesterol serves, among other things, as a precursor to steroid hormones and bile acids.
The cholesterol is converted into the sex hormones via precursors

Testosterone,
Estradiol and
Progesterone,

and converted into the adrenal hormones cortisol and aldosterone.
The two bile acids cholic acid and glycolic acid also come from cholesterol. In addition, an intermediate product in cholesterol biosynthesis, 7-dehydrocholesterol, is used to form vitamin D3 from UV light.

Admission and dismantling

Because cholesterol for humans vital Is sterol, it becomes too over 90% from the body self made.
In an adult, that means one production from 1-2g per day. The cholesterol uptake from the intestine is around 0.1-0.3g per day and can be increased to a maximum of 0.5g.

The basic substance for cholesterol synthesis is the "activated acetic acid"(Acetyl-CoA). This becomes over Mevalonic acid (Mevalonat) after a few steps Isopentenyl diphosphate manufactured. After a ring closure Squalene to Lanosterol after numerous enzymatic reactions the cholesterol.

The excretion of cholesterol takes place via the liverby keeping the cholesterol in the form of Bile acids in the Gallbladder is released and from there reaches the intestine. The body needs bile acids to remove insoluble substances from the water Intestines to reabsorb. This also includes the absorption of cholesterol.

But there about 90% the bile acids back from the intestines absorbed the excretion of cholesterol is relative ineffective. Some drugs that bind bile acids can increase the excretion of cholesterol. However, this leads to a counter-regulation mechanism in the liver and thereby to a relative increase in the Cholesterol synthesis, or increased cholesterol absorption from the blood.

Regulatory mechanisms

There are numerous mechanisms that balance the

recorded,
self produced and
required Regulate cholesterol.

The most important mechanism is the HMG CoA reductase inhibition. This is the most important enzyme in cholesterol biosynthesis and is produced by a Feedback inhibited by cholesterol itself.

So inhibits Cholesterol, or its precursors, the cholesterol-forming enzyme and the cholesterol synthesis, is stopped. this is the most direct Way of cholesterol regulation.
In addition, there are numerous other ways that at the level of the Gene regulation function. For example, activate the proteins

SCAP,
Insig-1 and
Insig-2 proteolysis of SREBPs in the presence of cholesterol, which then regulate genes that control the synthesis of cholesterol.

Cholesterol transport

Because cholesterol in water insoluble it has to be transported in blood Proteins be bound. These are called Lipoproteins designated.

After absorption from the intestine, the cholesterol is removed from Chylomicrons recorded. These transport the cholesterol to the liver. Other lipoproteins (VLDL, IDL and LDL) transport the self-made cholesterol from the Liver to tissues and are therefore also called the "bad“Called cholesterol.

The HDL however, take up the cholesterol from the tissues and transport it back to the liver. That is why they are known as "good cholesterol".

The "angry“LDL is removed from the blood through two different routes reduced. Most of the LDL is via the "LDL receptor pathway“Metabolized. These receptors are found on almost all cells of the arteries and liver cells and use them to absorb the “bad” cholesterol.
Another way is that Scavenger pathway. This leads to Dismantling and to storage of cholesterol in the blood vessels. Ultimately, this can lead to Plaque build-up and constipation of blood vessels and clinically in one Heart attack or stroke express.

Standard values

The Total cholesterol is used for values between 110-230 mg / dl specified. This applies to both women and men.

Of the LDL levels should be between women and men 70-180 mg / dl lie. In both cases, significantly higher values increase this S.stroke- and Heart attack risk.
The Triglycerides (TAG) should <150mg / dl be.
There HDL the "good cholesterol" is, there is no upper limit for this, the higher the HDL, the better. It should at least> 35mg / dl lie.

clinic

They are related to cholesterol familial Hypercholesterolemia and the formation of Gallstones.

Familial hypercholesterolemia is one innate Disturbance of cholesterol metabolism. It is associated with greatly increased cholesterol levels in the blood and can be caused by food intake Not to be influenced.
One of the known forms of hypercholesterolemia is the LDL receptors just incomplete developed or absent completely, so that the cholesterol cannot be absorbed from the blood. There is an increased uptake of LDL via the Scavenger pathway and thus to a significantly increased risk for Heart attacks and other vascular diseases at a younger age.

The most common form is autosomal dominant familial hypercholesterolemia with a prevalence of 1: 500. In laboratory tests, the patients often have very high total cholesterol and LDL cholesterol values, with normal values for HDL cholesterol and triglycerides. The disease can only be treated symptomatically by inhibiting the body's own synthesis. This is achieved by statins, which lead to the inhibition of HMG-CoA reductase and thereby inhibit the body's own build-up of cholesterol.

Gallstones arise from a change in the composition of the bile. As a result, the cholesterol can no longer be emulsified in large quantities in the bile and gallstones are formed. These consist of 80% partially cholesterol, 50% of the stones consist of pure cholesterol. The gallstones can go with no symptoms, but they can too Gallbladder infections, strong Pain and Drainage disorders of gall when the stones close the way. In these cases, the gallbladder often has to be removed. This also minimizes the risk of gallstones forming again, as gallstones can only arise in the gallbladder itself.

Medication

Fibrates are drugs that are used to lower triglycerides.
They increase the activity of lipoprotein lipase and at the same time reduce the concentration of apolipoprotein C III. As a result, they lower the triglyceride level very significantly.

The statins are currently the most effective drugs for lowering cholesterol. Statins inhibit HMG-CoA reductase and thereby lower the body's own cholesterol synthesis. Due to the significantly lower synthesis, the body absorbs LDL cholesterol from the blood in order to use it to form steroid hormones. This reduces the total cholesterol level and the LDL cholesterol by up to 60%.

Also read the article on the topic: Cholestyramine

Ezetimibe is a sterol transport inhibitor and prevents the absorption of cholesterol from the intestines. This lowers LDL cholesterol by 15-20%. It blocks the Niemann-Pick C1-Like 1 protein (NPC1L1), which sits on the enterocyte membrane of the small intestine wall and is necessary for the absorption of cholesterol from the intestine.

prophylaxis

In some studies there was a link between high cholesterol and Vascular disease being represented.
To lower the cholesterol level, one can use the above Medication be taken. However, one can also

little high-fat food and
much Move

Significantly lower cholesterol levels and thus the risk of heart attack or stroke.

According to the recommendations of the German Nutrition Society should pay attention to the following points:
The food should be as possible low fat be prepared, preferably using Vegetable oil.

Fat flesh,
Offal,
sausage,
cheese and egg yolk

should be rarely eaten, but fresh fruit and vegetables several times a day. Adequate exercise and abstaining from alcohol further reduce the risk.

Summary

cholesterol is a vital substance for the body and is the basic substance for the formation of numerous Hormones (Sex hormones, glucocorticoids).

It arises in the liver via a complicated mechanism from the activated acetic acid (Acetyl-CoA). The most important enzyme in the body's own synthesis of cholesterol is HMG-CoA reductase.

Just one less Part of the cholesterol gets over the daily food absorbed from the intestine. The cholesterol is a water-insoluble Substance and has to be different Lipoproteins bound to be transported in the blood. With the help of these transport proteins, it is transported to the tissues and back to the liver.

In some studies it has been shown that years of significantly increased cholesterol levels with a increased Risk for Vascular disease and thus stroke and Heart attack accompanied.
These are diseases that are clearly associated with high cholesterol innate familial Hypercholesterolemia and the Gallstone disease.

Effective drugs for lowering cholesterol are primarily those