In line with its mission, the Editorial Board of MedTvoiLokony makes every effort to provide reliable medical content supported by the latest scientific knowledge. The additional flag “Checked Content” indicates that the article has been reviewed by or written directly by a physician. This two-step verification: a medical journalist and a doctor allows us to provide the highest quality content in line with current medical knowledge.
Our commitment in this area has been appreciated, among others, by by the Association of Journalists for Health, which awarded the Editorial Board of MedTvoiLokony with the honorary title of the Great Educator.
We often talk about intricate and health-related topics, although we are not able to fully explain them properly. By saying “the pituitary gland” most of us know where it is located in the human body. Some remember that it secretes hormones that are important to the body. However, the vast majority have come across the term “tumor” or “pituitary adenoma”, which only confirms how important and, unfortunately, relatively frequent, this group of diseases is.
Let’s start with a reminder of where and what the pituitary gland is responsible for. It is a small, bean-shaped structure approximately 0,6 x 0,9 x 1,3 cm in size, located in the center of the skull. Its exact location in the so-called in the Turkish saddle, in close proximity to the cranial nerves, the intersection of the optic nerves and blood vessels.
The pituitary gland consists of two main parts known as the anterior and posterior pituitary gland. This division is derived from the different origins of the individual parts, where the front lobe is made of the glandular part, and the posterior lobe is made of the nerve part, and is an anatomical part of the brain structures. This is of great importance as the functions of both lobes differ significantly. The anterior lobe consists of a group of five types of glandular cells that are capable of producing the so-called tropic hormones, which are released into the peripheral blood and control the activity of other endocrine glands. They both stimulate and inhibit the glands under their control. The group of hormones in question includes: GH – somatotropin, i.e. growth hormone, PRL – prolactin, TSH – thyrotropin, LH – lutropin, FSH – follitropin and ACTH – corticotropin. Each of the above hormones has its main gland, organ or target tissues, such as the thyroid gland for thyrotropin, the adrenal cortex for ACTH, and finally the ovaries for LH and FSH.
The posterior lobe serves as a storage facility for neurohormones: vasopressin and oxytocin. The function of both lobes is strictly controlled and regulated by the superior center, which is the hypothalamus for the pituitary. It should be noted here that the entire hormonal control process is subject to, inter alia, feedback with the numerous complexities of the functioning of the endocrine system.
Pituitary tumors account for approximately 10-15% of intracranial tumors and are the most common cause of hypothalamic-pituitary dysfunction. The vast majority of these tumors are benign and slow growing.
One of the divisions is based on the determination of the hormonal activity of the tumor: hormonally inactive, i.e. non-secreting, and hormonally active (hormone-secreting) tumors. An abnormally proliferating cell line that secretes a certain hormone can produce huge amounts of it. Depending on the type of altered cells, the following tumors are distinguished: prolactin, somatotropin, corticotropin, gonadrotropin and thyrotropin tumors. Another division of adenomas takes into account their size, distinguishing microadenomas <1 cm in diameter and macroadenomas ≥ 1 cm.
As mentioned above, adenomas can produce large amounts of a given hormone and thus cause symptoms of hyperactivity, depending on the type of hormone secreted. Hypothyroidism in the course of adenoma is less common.
The second group of symptoms, which may additionally appear in the course of the disease, are symptoms resulting from the pressure of the growing tumor, the macroadenoma, on the adjacent structures. In this case, we are talking about the “mass effect”. These symptoms may include various neurological symptoms, disturbances in sleep and wakefulness, disturbed feelings of thirst and appetite, headaches, or the emergence of visual disturbances consisting in limited visual field.
Anterior pituitary adenoma secreting prolactin
The most common pituitary adenoma is a prolactin-secreting tumor – prolactinoma. The symptoms resulting from hyperprolactinaemia mainly affect the reproductive system. Excess prolactin causes, among others inhibition of the production of LH and FSH, i.e. it affects the work of the ovaries and, consequently, the deficiency of estrogens and progesterone. Menstrual disorders or their absence, decreased libido or infertility are the main reasons why a patient visits a gynecologist. The often occurring galactorrhea, i.e. the secretion of milk from the mammary glands, not related to pregnancy or puerperium, forces the woman to seek help from a doctor. These hormonal changes also lead to bone loss and osteoporosis. Symptoms do not always occur together and additional research is required to make a diagnosis. Hyperprolactinemia itself does not immediately mean a pituitary tumor, because it accompanies many physiological conditions, such as pregnancy, stress or sleep, and can be a side effect of drugs or also occur in the course of other diseases. Nevertheless, the appearance of abnormal symptoms, which may suggest a proliferative change in the pituitary gland, is an absolute indication for a visit to a doctor.
Diagnosis and treatment
One of the criteria that requires extension of diagnostics after excluding other causes of its occurrence is hyperprolactinemia. The purpose of further procedures is to visualize changes in the pituitary gland in imaging tests. An X-ray examination (X-ray) is available to assess the shape and size of the Turkish saddle and the presence of calcifications in the tissues. Computed tomography with the use of a contrast agent provides much more information on the soft tissues and the size of the tumor. Unfortunately, its usefulness is limited in microadenomas, for which magnetic resonance (MR) imaging is the best. When a larger pituitary tumor is suspected, an ophthalmological examination is necessary to assess the presence and degree of visual field disturbances resulting from tumor growth and the “mass effect”, which may often require urgent intervention.
- Check out what an empty saddle assembly is
Treatment of a prolactin tumor includes pharmacotherapy and surgery. The vast majority of adenomas respond well to conservative treatment with dopamine agonists. It is possible to inhibit further tumor growth, lead to its reduction, and even in some cases to the disappearance of the tumor, and the normalization of prolactin levels is achieved. It should be noted that this is a long-term treatment that requires discipline in taking medications, as their discontinuation leads to a relapse of the disease with an increase in prolactin levels and tumor regrowth.
Surgical treatment, in the case of prolactinoma, is reserved for situations of resistance to pharmacological treatment or extremely poor drug tolerance. Removal of the tumor should be performed in highly specialized neurosurgical centers. The success of the operation depends largely on the size of the tumor, but there is always a certain relapse rate.
Radiotherapy is considered in the case of pituitary tumors that are inoperable or not completely removed during previous operations.
Pituitary adenomas constitute a large group of diseases that require the cooperation of a gynecologist, endocrinologist, radiologist, ophthalmologist and neurosurgeon. Symptoms can develop insidiously, leading to widespread changes, only to suddenly manifest their presence at some point. It is important not to underestimate any symptoms, because only imaging diagnostics, combined with laboratory tests and a clinical picture together with a detailed history, can give a certain diagnosis. Further treatment requires a thorough case-by-case analysis, because although the goal of treatment is the same (hormonal normalization and tumor removal), the choice of the therapeutic path and prognosis differs slightly between different types of tumors.