Adrenal glands are small triangular-shaped organs, two in number, which lie just above the kidneys. In man an adrenal gland is actually a combination of two glands which are quite different in function. The inner core is called the medulla which is completely surrounded by the cortex.
The adrenal medulla manufactures a hormone called adrenalin, or epinephrine. This is a very potent substance produced in small quantities and secreted into the blood stream as the tissues demand it for their utilization. Its action is to stimulate all body metabolism; it elevates the blood pressure, accelerates the heart, raises the sugar content of the blood, and has many other stimulating effects. This endocrine gland is apparently the only one under direct control of the nervous system. At times of stress, such as fright or fear, the medulla is stimulated to secrete its adrenalin. This seemingly places the individual in a stimulated state, better prepared for anticipated battle or reaction to the frightening circumstances. At times of any mental or physical strain, increased production of adrenalin may occur. At all times the production is just sufficient to meet the tissues’ demands, according to their activity or anticipated activity.
The adrenal cortex produces a variety of hormones, commonly referred to as corticosteroids. The more important hormones are concerned with the control of the equilibrium of salt and water in the body and with the metabolism of fats, proteins, carbohydrates, and some other chemicals. These hormones may mimic the action of other hormones in the body; for example, one is similar to the female sex hormone while another apes the male sex hormone.
Abnormal function of the adrenal cortex can produce a variety of specific diseases and deformities. These are dependent, of course, on which hormones are excessive and which are depressed, and also on the time of life when the disease takes its onset.
The main surgical disorder of the adrenal glands is tumor. These may be benign or malignant. Tumors causing a single hormone disturbance are not nearly so common as those affecting the production of several of the gland’s hormones. A complexity of combinations may occur. The therapy of adrenal tumors of course is by their surgical removal. Much preoperative study is necessary to confirm the existence of such tumor, utilizing an array of blood tests, x-ray studies, and metabolism tests.
Surgical approach to the adrenal gland is through a flank incision or through the front of the abdominal wall. Occasionally it is necessary to approach both adrenal glands concurrently; this is usually through the front of the abdomen. Removal of an adrenal gland is called adrenalectomy; this may be a partial or total or of one or both glands. In some cases x-ray may be used as an adjunct to surgery, or x-ray alone may be used.
In most instances, where there is a deficiency of one of the hormones of the adrenals, the patient can be normally maintained by artificially administering it. This may be in the form of oral medicines, injections, or implanting a slowly dissolving pellet underneath the skin for a longer lasting effect.
In more recent years, adrenalectomy has been employed for the treatment of high blood pressure, the theory based on eliminating the adrenal medulla hormonal effect. The usefulness of this operation has not been applicable to all types of high blood pressure, and some aspects of its value are still under investigation. Adrenalectomy has also been advocated in certain cases of cancer where the hormones are known to have an effect on the rate of growth of the malignancy.
Medical and surgical investigation of the adrenal glands in recent years has provided much practical information of the physiology and abnormalities of these vital organs. Future advances appear most promising for improved treatment methods of diseases of several body systems.