Synonyms
Glandula suprarenalis, Glandula adrenalis The adrenal glands are important hormone glands in the human body. Every person has 2 adrenal glands. The adrenal gland lies on top of the kidneys like a kind of cap.
It is about 4 cm long and 3 cm wide and weighs 10 grams on average. The organ can be roughly divided into two sections: The inner adrenal medulla (Medulla glandulae suprarenalis) is functionally part of the sympathetic nervous system, since it is here that the hormone or transmitter substances adrenaline and noradrenaline, also called catecholamines, are produced. The adrenal medulla is surrounded from the outside by the adrenal cortex (Cortex glandulae suprarenalis), which has important functions in the hormonal balance of the body.
It also represents the main part of the organ and is bordered on the outside by a capsule of connective tissue (Capsula fibrosa). The adrenal cortex can in turn be divided into three sections according to the function and arrangement of the cells: from the outside to the inside, there is the zona glomerulosa (ball or ball-shaped arrangement of the cells), zona fasciculata (columnar arrangement) and zona reticularis (net-like arrangement). Through the hormones produced, the adrenal cortex is able to intervene in the body’s water, sugar and mineral balance. The hormones synthesized by the adrenal cortex all belong to the group of steroid hormones because they have the same precursor molecule cholesterol (basic chemical structure of sterane).
Diseases of the adrenal cortex
A distinction is generally made between over- and under-functions of the adrenal gland, depending on whether too much or too little hormone is produced. The causes are manifold. Conn syndrome (also known as primary hyperaldosteronism) is caused by increased production of aldosterone in the glomerular zone of the adrenal cortex.
This is mainly caused by benign tumors, also called adenomas, or a simple enlargement (hyperplasia) of the zona glomerulosa, the cause of which has not yet been clarified. The increased supply of aldosterone leads to an increase in blood pressure and a decrease in the potassium level in the blood. This usually leads to headaches, muscle weakness, constipation and increased and frequent urination, often at night (polyuria, nocturia), because the washed out potassium carries water with it.
In addition, patients often complain of increased thirst (polydipsia). The shift in the potassium balance can also lead to cardiac arrhythmia. However, there is also a form of the disease in which the potassium level is not changed, i.e. it is within the normal range.
If the disease is based on a tumor, the symptoms can be controlled by surgical removal of the tumor. If it is a case of hyperplasia, aldosterone antagonists are given to counteract the effect of the body’s own aldosterone, such as spironolactone. In addition, blood pressure usually has to be brought into the normal range with suitable medication.
Cushing’s disease is caused by increased production of cortisol from the zona fasciculata of the adrenal cortex. This occurs, for example, in tumors of the pituitary gland. The tumor produces increased amounts of the hormone ACTH, which stimulates the adrenal cortex to produce cortisol.
Other causes are an enlargement of the adrenal gland, either due to a tumor or increased growth on both sides (hyperplasia). The symptoms that the patients then show are also known as Cushing’s syndrome and are relatively characteristic of the disease: patients suffer from trunk obesity with fat deposits on the trunk, especially in the abdominal area, whereas the arms and legs are very thin. In addition, there is often a thickened neck (“bull’s neck”) and a round face (“moon face”).
The patients’ skin resembles parchment paper, as it often becomes very thin, and the bones become brittle (osteoporosis). Above all, the carbohydrate metabolism is also disturbed, which can lead to diabetes with increased thirst and increased urination. Long-term administration of cortisone as a drug can also lead to Cushing’s disease.
Therefore, care must be taken to ensure that the patient only takes these drugs for as long as necessary. A tumor should be removed for treatment, if possible. If this is not the case, drugs are given which inhibit the overproduction of cortisol.
If not enough cortisol is produced by the adrenal cortex, this is called adrenal cortex insufficiency. Depending on the cause, a distinction is made between a primary, secondary and tertiary form.If the cause lies in the adrenal cortex itself, it is called primary adrenal cortex insufficiency or Addison’s disease. In most cases, this is caused by autoimmune reactions against cells of the adrenal cortex, but it can also be triggered by certain infectious diseases such as tuberculosis or AIDS.
Tumors can also be responsible for this. The pituitary gland reacts to the reduced cortisol supply via a feedback mechanism with an increased release of ACTH. However, the ACTH-producing cells in the pituitary gland also produce another hormone: MSH (melanocyte stimulating hormone).
This hormone stimulates the melanin-producing cells of the skin to produce pigment. As a result, patients with Addison’s disease usually have a very tinted skin. If the cause lies outside the adrenal gland, this is known as secondary or tertiary adrenal cortex insufficiency.
This is the case with diseases of the hypothalamus (tertiary) or the pituitary gland (secondary), which are then no longer able to produce sufficient CRH or ACTH, respectively, and the adrenal cortex receives too few stimuli for cortisol production. This can be the case with tumor diseases, inflammation and other diseases of these brain areas. However, symptoms are also possible after the corstisone has been discontinued too quickly during cortisone therapy: due to long-term corstisone administration, the body has become accustomed to high corstisone levels in the blood.
The pituitary gland hardly ever releases ACTH. If the treatment is discontinued very quickly, the hypothalamus and pituitary gland cannot adjust so quickly. The body then rapidly lacks cortisol.
This can lead to an “Addison crisis” with rapid drop in blood pressure, vomiting and shock. For this reason, care should always be taken to let cortisone therapy slowly wear off in order to give the body the opportunity to supply itself with the necessary hormone dose again. Possible symptoms that adrenal insufficiency can cause are Lack of drive, low blood pressure, nausea with vomiting, fatigue, weight loss, loss of pubic hair and dizziness.
However, many symptoms appear very late in the course of the disease, so that often large parts of the adrenal gland are already destroyed. The therapy of choice is a substitution of the missing hormones. You can also find out more about Addison’s disease under our topic: Addison’s disease and Addison’s crisis.
Which might also be of interest to you: Symptoms of low blood pressureThe pheochromocytoma is a mostly benign tumor (about 90%) that produces catecholamines (norepinephrine and adrenaline). In the majority of cases, it is located in the adrenal medulla, but it can also be localized in other parts of the body, such as the border strand, a nerve plexus running parallel to the spinal column. Due to the increased and uncontrolled release of adrenaline and especially norepinephrine, patients with pheochromocytoma suffer from permanent blood pressure increases, or from sudden hypertension crises, in which life-threatening values can be reached, as cerebral hemorrhages or heart attacks can no longer be ruled out.
Accompanying symptoms are excessive sweating, dizziness, headaches and palpitations. The pheochromocytoma is usually discovered quite late. The method of choice when this disease is suspected is the determination of catecholamines in the urine as well as in the blood.
Therapy of choice is surgical removal of the tumor, which may be accompanied by removal of the adrenal gland. An underfunction of the adrenal medulla is also possible, but rare, e.g. after surgical damage to the adrenal gland. If catecholamines are no longer produced in sufficient quantities, the body has difficulty maintaining blood pressure. This can lead to dizzy spells with fainting spells. Therapeutic agents are used to raise blood pressure.
