Acromegaly is a pathological enlargement of individual parts of the body associated with increased production of somatotropic hormone (growth hormone) by the anterior pituitary lobe as a result of its tumor lesion. It occurs in adults and is manifested by enlargement of facial features (nose, ears, lips, lower jaw), enlargement of feet and hands, constant headaches and joint pains, violation of sexual and reproductive functions in men and women. It is diagnosed according to hormonal tests, skull x-ray, brain MRI. Treatment is carried out by medication, radiation and surgical methods.
ICD 10
E22.0 Acromegaly and pituitary gigantism
Meaning
Acromegaly begins to develop after the body stops growing. Gradually, over a long period, the symptoms increase, and changes in appearance occur. On average, acromegaly is diagnosed 7 years after the actual onset of the disease. The disease is equally common among women and men, mainly at the age of 40-60 years. Acromegaly is a rare endocrine pathology and is observed in 40 people per 1 million population. Elevated levels of growth hormone in the blood cause early mortality from cancer, lung, and cardiovascular diseases.
Causes
The secretion of somatotropic hormone (somatotropin, STH) is carried out by the pituitary gland. In childhood, the somatotropic hormone controls the processes of formation of the musculoskeletal skeleton and linear growth, and in adults it controls carbohydrate, fat, water-salt metabolism. The secretion of growth hormone is regulated by the hypothalamus, which produces special neural secrets: somatoliberin (stimulates the production of STH) and somatostatin (inhibits the production of STH).
Normally, the content of somatotropin in the blood fluctuates during the day, reaching its maximum in the pre-morning hours. In patients with acromegaly, there is not only an increase in the concentration of STH in the blood, but also a violation of the normal rhythm of its secretion. The cells of the anterior pituitary lobe, for various reasons, do not obey the regulatory influence of the hypothalamus and begin to actively multiply. The proliferation of pituitary cells leads to the appearance of a benign glandular tumor – pituitary adenoma, which intensively produces somatotropin. The size of the adenoma can reach several centimeters and exceed the size of the gland itself, squeezing and destroying normal pituitary cells.
In 45% of patients with acromegaly, pituitary tumors produce only somatotropin, in another 30% they additionally produce prolactin, in the remaining 25%, in addition, they secrete luteinizing, follicle-stimulating, thyroid-stimulating hormones, A-subunit. In 99%, it is the pituitary adenoma that causes acromegaly. The factors causing the development of pituitary adenoma are traumatic brain injuries, hypothalamic tumors, chronic inflammation of the sinuses (sinusitis). A certain role in the development of acromegaly is assigned to heredity, since the disease is more often observed in relatives.
Pathogenesis
In childhood and adolescence, against the background of continued growth, chronic hypersecretion of STH causes gigantism, characterized by an excessive but relatively proportional increase in bones, organs and soft tissues. With the completion of physiological growth and ossification of the skeleton, disorders of the type of acromegaly develop – disproportionate thickening of bones, enlargement of internal organs and characteristic metabolic disorders. With acromegaly, hypertrophy of the parenchyma and stroma of internal organs occurs: heart, lungs, pancreas, liver, spleen, intestines. The proliferation of connective tissue leads to sclerotic changes in these organs, the threat of the development of benign and malignant tumors, including endocrine, increases.
Classification
Acromegaly is characterized by a long, long-term course. Depending on the severity of symptoms in the development of acromegaly, there are several stages:
- The stage of preacromegaly – initial, weakly expressed signs of the disease appear. At this stage, acromegaly is rarely diagnosed, solely by indicators of the level of somatotropic hormone in the blood and brain CT.
- Hypertrophic stage – there is a pronounced symptomatology of acromegaly.
- The tumor stage – the symptoms of compression of adjacent parts of the brain (increased intracranial pressure, nervous and ocular disorders) come to the fore.
- The stage of cachexia is exhaustion as the outcome of acromegaly.
Acromegaly symptoms
Manifestations of acromegaly may be due to an excess of somatotropin or the effect of pituitary adenoma on the optic nerves and nearby brain structures.
Excess growth hormone causes characteristic changes in the appearance of patients with acromegaly: enlargement of the lower jaw, zygomatic bones, brow arches, hypertrophy of the lips, nose, ears, leading to coarsening of facial features. With an increase in the lower jaw, there is a divergence of the interdental spaces and a change in the bite. There is an increase in the tongue (macroglossia), on which teeth marks are imprinted. Due to hypertrophy of the tongue, larynx and vocal cords, the voice changes – it becomes low and hoarse. Changes in appearance in acromegaly occur gradually, imperceptibly for the patient himself. There is a thickening of the fingers, an increase in the size of the skull, feet and hands so much that the patient is forced to purchase hats, shoes and gloves several sizes larger than before.
With acromegaly, the skeleton is deformed: the spine is curved, the chest increases in anteroposterior size, acquiring a barrel shape, the intercostal spaces expand. Developing hypertrophy of connective and cartilaginous tissues causes deformation and restriction of joint mobility, arthralgia.
Excessive sweating and sebum secretion are noted, due to an increase in the number and increased activity of sweat and sebaceous glands. The skin of patients with acromegaly thickens, thickens, gathers into deep folds, especially in the scalp.
There is an increase in the size of muscles and internal organs (heart, liver, kidneys) with a gradual increasing dystrophy of muscle fibers. Patients begin to worry about weakness, fatigue, progressive decrease in performance. Myocardial hypertrophy develops, which is then replaced by myocardiodystrophy and increasing heart failure. A third of patients with acromegaly have arterial hypertension, almost 90% develop sleep apnea syndrome associated with hypertrophy of the soft tissues of the upper respiratory tract and disruption of the respiratory center.
With acromegaly, sexual function suffers. In most women, with an excess of prolactin and a deficiency of gonadotropins, menstrual disorders and infertility develop, galactorrhea appears – milk discharge from the nipples that is not caused by pregnancy and childbirth. In 30% of men, there is a decrease in sexual potency. Hyposecretion of antidiuretic hormone in acromegaly is manifested by the development of diabetes insipidus.
As the pituitary tumor increases and nerves and tissues are compressed, there is an increase in intracranial pressure, photophobia, double vision, pain in the cheekbones and forehead, dizziness, vomiting, decreased hearing and sense of smell, numbness of the extremities. Patients suffering from acromegaly have an increased risk of developing tumors of the thyroid gland, gastrointestinal tract, uterus.
Complications
The course of acromegaly is accompanied by the development of complications from almost all organs. Heart hypertrophy, myocardiodystrophy, arterial hypertension, and heart failure are most common in patients with acromegaly. More than a third of patients develop diabetes mellitus, liver dystrophy and pulmonary emphysema are observed.
Hyperproduction of growth factors in acromegaly leads to the development of tumors of various organs, both benign and malignant. Acromegaly is often accompanied by diffuse or nodular goiter, fibrocystic mastopathy, adenomatous hyperplasia of the adrenal glands, polycystic ovaries, uterine fibroids, intestinal polyposis. Developing pituitary insufficiency (panhypopituitarism) is caused by compression and destruction of the pituitary tumor.
Diagnostics
In the later stages (5-6 years after the onset of the disease), acromegaly can be suspected on the basis of an increase in body parts and other external signs noticeable during examination. In such cases, the patient is referred to an endocrinologist’s consultation and tests for laboratory diagnostics. The main laboratory criteria for the diagnosis of acromegaly are the determination of the content in the blood:
- somatotropic hormone in the morning and after the glucose test;
- IGF I is an insulin-like growth factor.
An increase in the level of somatotropin is determined in almost all patients with acromegaly. An oral test with a glucose load in acromegaly involves determining the initial value of STH, and then after taking glucose – after half an hour, an hour, 1.5 and 2 hours. Normally, after taking glucose, the level of somatotropic hormone decreases, and in the active phase of acromegaly, on the contrary, its increase is noted. Conducting a glucose tolerance test is particularly informative in cases of a moderate increase in the level of STH, or its normal values. Also, a glucose load test is used to evaluate the effectiveness of acromegaly treatment.
Somatotropic hormone acts on the body through insulin-like growth factors (IGF). The concentration in the blood plasma of IGF I reflects the total release of STH per day. An increase in IGF I in the blood of an adult directly indicates the development of acromegaly.
During ophthalmological examination in patients with acromegaly, there is a narrowing of the visual fields, because anatomically the visual pathways are located in the brain next to the pituitary gland. Radiography of the skull reveals an increase in the size of the Turkish saddle, where the pituitary gland is located. To visualize a pituitary tumor, computer diagnostics and brain MRI are performed. In addition, patients with acromegaly are examined for various complications: intestinal polyposis, diabetes mellitus, multi-nodular goiter, etc.
Acromegaly treatment
In acromegaly, the main goal of treatment is to achieve remission of the disease by eliminating hypersecretion of somatotropin and normalizing the concentration of IGF I. For the treatment of acromegaly, modern endocrinology uses medical, surgical, radiation and combined methods.
To normalize the level of somatotropin in the blood, somatostatin analogues are prescribed – a neurosecret of the hypothalamus that suppresses the secretion of growth hormone (octreotide, lanreotide). With acromegaly, the appointment of sex hormones, dopamine agonists (bromocriptine, cabergoline) is indicated. Subsequently, a one-time gamma or radiation therapy is usually performed on the pituitary gland area.
In acromegaly, surgical removal of the tumor at the base of the skull through the sphenoid bone is the most effective. With small sizes of adenomas after surgery, 85% of patients have normalization of somatotropin levels and persistent remission of the disease. With a significant tumor size, the percentage of cure as a result of the first operation reaches 30%. The mortality rate for surgical treatment of acromegaly ranges from 0.2 to 5%.
Prognosis and prevention
The lack of treatment for acromegaly leads to disability of patients of active and working age, increases the risk of premature mortality. With acromegaly, life expectancy is reduced: 90% of patients do not live to 60 years. Death usually occurs as a result of cardiovascular diseases. The results of surgical treatment of acromegaly are better with small sizes of adenomas. With large tumors of the pituitary gland, the frequency of their relapses sharply increases.
To prevent acromegaly, head injuries should be avoided, and chronic foci of nasopharyngeal infection should be sanitized. Early detection of acromegaly and normalization of growth hormone levels will help to avoid complications and cause persistent remission of the disease.