Introduction
Low blood pressure (hypotension) is defined as a blood pressure of less than 105/60 mmHg. The standard value of blood pressure is 120/80 mmHg. Low blood pressure can manifest itself in various ways. A too low blood pressure (hypotension) can be accompanied by certain symptoms (e.g. dizziness with circulatory collapse (syncope), visual disturbances, headaches, etc.). It is therefore important for the treating physician to find the underlying cause in order to be able to raise the blood pressure adequately.
Causes of hypotension
The causes of low blood pressure can basically be divided into four different categories: Hypotension is very common in thin women in adolescence. Physical or mental stress in private or professional life can also be the cause of low blood pressure. Not infrequently, low blood pressure can be temporarily caused by a lack of fluid intake or electrolyte imbalance.
Since hypotension can have very different causes, a comprehensive diagnosis should be carried out (examination of the vascular system, imaging of the thyroid gland, collection of venous blood to determine the electrolytes, etc.) The patient’s medical history should include certain questions, which can help to determine the cause of the hypotension.
- Organic causes (e.g.
diseases of the heart or vascular system, thyroid or adrenal glands) or due to certain environmental conditions (e.g. stress or underweight)
- Congenital constitutional form of low blood pressure (hypotension)
- Shock situations (e.g. allergic or septic shock)
- Orthostatic adaptation disorder after changing position from lying to standing position
Heart diseases such as arrhythmia or heart failure can impair the work of the heart and lead to low blood pressure. Cardiac arrhythmias can lead to reduced blood ejection from the heart and thus to low blood pressure.
This reduced ejection (cardiac output) occurs mainly during circulating excitation of the heart (for example, reentry tachycardia) or in situations where the heart is functionally stopped (for example, ventricular fibrillation). In these cases, less blood volume per time reaches the central and peripheral arterial vessels. Since a continuous supply of oxygen to the sensitive neurons of the brain is essential and can no longer be guaranteed in such a case, the typical symptoms such as dizziness, syncope, paleness, etc.
may occur. Even in the case of a weakness of the heart muscle (cardiac insufficiency), the heart ejects less blood from the aorta and the truncus pulmonalis. Clinically, this is identical to reduced blood ejection as in certain cardiac arrhythmias.
Low blood pressure can also occur in a condition known as aortic arch syndrome. In this case there is a narrowing (stenosis) directly before the exit of the arterial vessels (artery carotis communis) that supply the brain. In aortic arch syndrome, the lower extremities are typically still sufficiently supplied with blood, while the brain is undersupplied arterially.
This is why the typical symptoms of arterial hypotension occur. Vascular diseases such as weakness of the venous wall can lead to hypotension. Due to a disturbance of the muscular or connective tissue part, it can lead to dilatation of the veins (“varicose veins“).
The blood sinks into these veins and turbulence forms due to the slowed blood flow. The blood literally “stops” and sinks. Varicose veins usually occur in the legs, where the blood consequently sinks.
This results in low blood pressure in the central circulation. An undersupply of the arterial vessels of the brain with a possible circulatory collapse can result. Along with the adrenal gland, the thyroid gland is one of the organs that is involved in the regulation of blood pressure by releasing its hormones.
Of important importance here are the two hormones triiodothyronine (T3) and thyroxine (T4), which are produced by the thyroid gland and released into the blood. These hormones act on various cells and tissues and can thus influence blood pressure, among other things. They can increase the work of the heart (among other things by increasing the activity of the sodium/potassium ATPase) and thus also the blood pressure.In the case of hypothyroidism, there is a deficiency of these hormones.
Hypothyroidism can therefore lead to low blood pressure (hypotension). Very often, hypothyroidism is caused by an autoimmune disease (Hashimoto’s thyroiditis, mainly in young women). Therefore, especially young women with complaints of low blood pressure (dizziness, listlessness, tiredness, paleness, visual disturbance with star vision) should be considered for a thyroid-related genesis.
Addison’s disease In addition to sex hormones (androgens), mineralocorticoids (especially aldosterone) and glucocorticoids (especially cortisol) are also produced in the adrenal cortex. Especially aldosterone and cortisol develop an increase in arterial blood pressure. Hypotension can result in diseases with an underfunction (for example Addison’s disease or tumor diseases).
Addison’s disease results in an underfunction of the adrenal cortex. As described above, blood pressure-increasing hormones such as aldosterone and cortisol are produced here. In the case of hypofunction, these blood pressure-increasing hormone effects are absent.
As a result, low blood pressure (hypotension) can occur. Do you have any further questions about hypothyroidism? First of all, the occurrence of low blood pressure in stressful situations appears paradoxical.
Normally, stress situations constrict the arterial vessels (vasoconstriction) in order to increase blood pressure and thereby meet the increased demands of physical exertion. However, when long periods of stress occur, this control circuit fails. Vasoconstriction (narrowing of blood vessels) can no longer be maintained and low blood pressure (hypotension) may develop.
Therefore, care should be taken to transform the so-called “negative” stress into a “positive” stress. Periods of stress should be limited in time in order to avoid this dysregulation of vasoconstriction. Do you suffer from stress?
Even young age can in principle lead to low blood pressure (hypotension). This is usually because younger people are very thin in some cases. Especially in adolescence, the body faces the challenge of growing fast.
The young people are very thin (often also due to “social pressure situations”). Their blood pressure is usually lower than that of adults. Up to about 20% of all children up to the age of 15 suffer a collapse once or several times due to a circulatory weakness.
Orthostatic dysregulation is the most common cause. The so-called vasovagal syncope also occurs very frequently. In this case, after getting up, a pathological drop in blood pressure occurs and the blood in the lower extremities sinks.
In this case the brain is temporarily undersupplied with blood and a circulatory collapse can develop. The processes of growing up described above with strong body growth combined with often very low blood pressure occurs more often in the female sex. Trigger for low blood pressure (hypotension) in this “life phase” can often also be a lack of fluid intake.
The body needs an increased intake of minerals and nutrients for growth. A potentially reversible cause of low blood pressure (hypotension) that can be prevented by simple measures is a lack of fluid intake. Since about 1.5 to 1.8 liters are lost daily through urine (in addition to other fluids, for example through breathing or sweating), the circulating blood volume in the vascular system must be maintained by sufficient fluid intake.
The average recommended amount of fluid intake of between 2 to 3 liters can be significantly increased by additional strain (e.g. sports). Basically, blood pressure in the vascular system is regulated by the mutual interplay of hydrostatic pressure (the pressure that the blood in the vessel exerts on the vessel wall and potentially wants to force fluid out of the vascular system) and colloid-osmotic pressure (proteins of the blood plasma that hold the fluid in the vascular system). An imbalance between these two pressures can lead to a change in blood volume and thus blood pressure.
For example, a lack of plasma proteins (especially albumin) leads to a loss of water in the vascular system and thus to a drop in blood pressure. In addition, an increased loss of fluid (for example as a result of injuries with bleeding) can lead to low blood pressure due to fluid loss.Frequent vomiting (vomiting), diarrhea (diarrhea) or increased urination in diabetes mellitus also cause increased fluid loss. A strong drop in blood pressure (hypotension) can in principle also be due to the side effects of medication.
For example, diuretic drugs such as diuretics (for example the frequently used loop diuretic) have a strong blood pressure-lowering effect. When treating with diuretics, blood pressure should therefore be measured in addition to regular electrolyte checks (especially potassium). In general, hypotension can also be caused by blood pressure-lowering drugs.
Especially in the early phase of a blood pressure-lowering therapy, strong hypotension can occur. Control measurements of the blood pressure should be taken regularly. Some psychotropic drugs also have an antihypertensive effect.
Tri- and tetracyclic antidepressants as well as certain antipsychotics from the group of phenothiazines are particularly worth mentioning. Hereditary disturbances of the target value for blood pressure in the regulating organs can also be a possible cause. These are primarily the stretch receptors (baroreceptors) in the carotid sinus of the aorta, the medulla oblongata as the circulatory center in the brain stem and the kidney as the regulator of volume with the central hormone renin.
The regulation of blood pressure is a complex unit of several organic systems, which can easily be brought out of balance by innate effects. A genetically determined adjustment of the target value for the “optimal” blood pressure is in principle possible in both directions. Thus, in addition to hypotension, hypertension can also occur due to the nature of the disorder.
