Acromegaly is a disease due to an excess of growth hormone production (also called growth hormone or GH for Growth Hormon). This causes a change in the appearance of the face, an increase in the size of the hands and feet and also many organs, causing the main symptoms and signs of the disease.
This is a rare condition, affecting about 60 to 70 cases per million inhabitants, which represents 3 to 5 cases per million inhabitants per year.
In adults, it is usually diagnosed between the ages of 30 and 40 years. Before puberty, the increase in GH causes gigantism or giganto-acromegaly.
The main cause of acromegaly is a benign (non-cancerous) tumor of the pituitary gland, a gland (also called pituitary gland), located in the brain that normally secretes several hormones including GH.
1) related to increased production of growth hormone
– The symptoms of acromegaly are primarily related to the effects of abnormally high production of GH and another hormone, IGF-1 (Insulin Growth Factor-1) which is “controlled” by GH :
They understand :
- an increase in the size of hands and feet;
- a change in the appearance of the face, with a bulging forehead, cheekbones and prominent eyebrows, a thickened nose, thickening of the lips, a gaping of the teeth, a thicker tongue, a “galoche” chin;
- Joint pain (arthralgia) or back pain (back pain), tingling or tingling of the hands associated with carpal tunnel syndrome due to thickening of the wrist bone compressing the median nerve;
- other symptoms, such as sweating, tiredness, hearing loss, voice changes, etc.
2) Related to the cause
– Other symptoms are related to the cause, that is to say, most often to the benign pituitary tumor which, by increasing the volume of the latter, can compress other brain structures and / or decrease the production of other pituitary hormones:
- headache (headache);
- vision problems;
- Decreased secretion of thyroid hormones causing chills, general slowing, constipation, slowing of heart beat, weight gain, sometimes with goitre;
- decreased secretion of adrenal hormones (fatigue, loss of appetite, decreased hair growth, hypotension …);
- decreased secretion of sex hormones (menstruation, impotence, infertility …).
– Excess secretion of GH is sometimes accompanied by increased production of another hormone, prolactin, which can cause an increase in the volume of breasts in men (gynecomastia) a secretion of milk and decreased libido in women and men, lengthening or stopping menstrual cycles in women …
– Acromegaly is often accompanied by other conditions such as diabetes, high blood pressure, sleep apnea, gall bladder stones, nodules, even thyroid cancer, and there is also an excess of colon cancer, hence some additional research sometimes requested (ultrasound of the thyroid, sleep apnea assessment, colonoscopy, etc.).
The symptoms appear very slowly, so that the diagnosis is usually made after several years of evolution (4 to more than 10 years). It is quite often initially on the physical appearance, when the person affected (or his entourage) notices that it can no longer put on his rings, changed shoe size and hat size.
Sometimes, too, they are photographs that highlight the abnormal changes of the face over time.
In the vast majority of cases (over 95%), the hypersecretion of growth hormone causing acromegaly is related to the development of a benign tumor of the pituitary (pituitary adenoma), a small gland (about the size of a chickpea), located at the bottom of the brain, about the height of the nose.
This tumor occurs most often unexpectedly: it is then called “sporadic”. In other cases, much rarer, acromegaly is linked to a genetic anomaly: there are other cases in the family and it can be associated with other pathologies.
Nevertheless, the opposition between sporadic and familial forms is increasingly difficult to maintain, since in sporadic forms (without other cases in the family) it has recently been shown that genetic mutations also exist. at the origin of the disease.
In the rare cases of familial forms, there is of course an increased risk of acromegaly. In general, the diagnosis of a case in the family leads to screening of other members of this family.
The diagnosis of acromegaly is quite easy (but only when you think about it), since it involves taking a blood test to determine the level of GH and IGF-1. In acromegaly, there is a high level of IGF-1 and GH, knowing that the secretion of GH is normally intermittent, but that in acromegaly, it is still high because it is no longer regulated. The definitive biological diagnosis is based on the glucose test. As glucose normally decreases GH secretion, oral glucose administration can detect, through successive blood tests, that in acromegaly, secretion of growth hormone remains high.
Once the hypersecretion of GH is affirmed, it must then find its origin. Today, the reference exam is a brain MRI that can show a pituitary tumor. In very rare cases, it is a tumor located elsewhere (most often in the brain, lung or pancreas) that secretes another hormone acting on the pituitary gland, GHRH stimulating the production of GH. A broader assessment is then made to find the origin of this abnormal secretion.
The treatment of acromegaly involves surgery, medications and, more rarely, radiotherapy.
- Surgical treatment
Surgical treatment is the preferred treatment for acromegaly, aiming to remove the benign tumor from the pituitary gland causing hypersecretion of GH. It can only be performed in very experienced hands, in this case those of neurosurgeons specializing in pituitary surgery.
Today, it is done nasally (so-called trans-sphenoidal pathway), either in microsurgery (using a microscope) or endoscopy. While this is the most logical approach, it is also difficult and a potential source of side effects. In some cases, prior medical treatment is performed; in other cases, the aim is to remove as much tumor mass as possible (so-called tumor reduction surgery) to improve the subsequent response to medical treatment.
- Medical treatment
Medical treatment can either complete the surgery or replace it when surgery is not possible. Several drugs in the class of somatostatin inhibitors are now prescribed in acromegaly. Delayed forms are currently available which allow for spaced injections. There is also an analog of the GH that, “taking the place of the latter,” can stop its action, but it requires several daily injections. Other drugs, such as dopaminergics, can also be used in acromegaly.
Currently, radiotherapy of the pituitary gland is rarely prescribed because of these side effects. Nevertheless, there are now techniques where the rays are very targeted, which greatly limit the harmful consequences of radiotherapy (GammaKnife, CyberKnife for example), and which may eventually complement the medical and / or surgical treatment.