Introduction
The pituitary gland is a pea-sized gland situated in the base of the brain. It plays a vital role in producing hormones such as adrenocorticotropic hormone (ACTH), helps the body respond to stress, follicle-stimulating hormone (FSH) stimulates the sperm and ovaries to produce estrogen, and thyroid-stimulating hormone (TSH) stimulates the thyroid to produce thyroid hormones. In addition, TSH is released by the pituitary gland to help the thyroid produce its own hormones, thyroxine (T4) and triiodothyronine (T3). Both of these hormones maintain the body’s metabolic rate.
If the pituitary gland does not function properly, it can cause various complications, and one such complication is thyrotropinoma.
What Is Thyrotropinoma?
Thyrotropinoma, also known as TSHoma, is a pituitary adenoma or tumor that occurs in the thyrotropic cells of the pituitary gland and secretes a thyroid-stimulating hormone or TSH that leads to overproduction of thyroid hormone, thus enlargement of the thyroid gland. This condition is termed hyperthyroidism. Thyrotropinoma is a rare type of tumor and generally affects people between the ages of 40 to 50, as many times this condition is undetected.
What Is the Classification of Thyrotropinoma?
Thyrotropin analysis of all the patients seen showed tumors with elevated TSH production as well as neoplasms with hyperproduction of other pituitary hormones. The clinical classification that is frequently used in endocrinology was founded on this observation. It distinguishes between the following types of thyrotropinoma:
TSH Is Being Secreted: All thyrotropins, up to 80 %, are produced by it. Increased release of just thyroid-stimulating hormone is one of its hallmarks.
Mixed: In 20 to 25 % of situations, it happens. It also produces other pituitary hormones, most frequently prolactin and somatostatin, in addition to TSH. Acromegaly and other clinical signs of hyperprolactinemia frequently conceal the symptoms of hyperthyroidism.
What Causes Thyrotropinoma?
Hyperthyroidism occurs when the thyroid gland produces too much thyroid hormone and can occur due to several reasons, but in the case of thyrotropinomas, Grave’s disease is considered the primary cause.
Grave’s Disease - It is an autoimmune disorder that causes overproduction of the thyroid hormone. Normally a healthy immune system produces a set of antibodies to handle any invading viruses and bacteria in the body. However, in Grave’s disease, the immune system is triggered for some unclear reasons, which leads to the overproduction of antibodies in the thyroid gland. This antibody is known as thyrotropin receptor antibody (TRAb), and it acts as the pituitary hormone and leads to the overproduction of the thyroid.
Sometimes, when a patient suffering from thyrotoxic becomes severely ill or, if left untreated, a thyroid storm, a type of hyperthyroidism, occurs.
What Are the Symptoms of Thyrotropinoma?
Some people may not have symptoms. However, some of the common visible symptoms of this condition include:
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Rapid heartbeat.
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Anxiety.
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Hand tremors.
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Nervousness.
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A swelling or lump in front of the neck.
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Muscle weakness.
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Weight loss.
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Difficulty sleeping.
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Brittle hair.
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Frequent bowel movements.
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Irregular menstrual cycle.
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Increased appetite.
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Irritability.
How Is Thyrotropinoma Diagnosed?
Firstly the doctor does a complete physical examination, records the complete medical history, and asks the patient about the symptoms and duration of the same. After the complete clinical evaluation to confirm the diagnosis, some tests are advised.
Blood Test: A blood test is advised to look for abnormal TSH and thyroxine (T4) levels. A healthcare professional will take the sample from the arm’s vein. A fine needle is inserted in the vein, and a minimal amount of blood is drawn out in a vial. Once the sample is collected, the needle is removed gently. The sample is sent to a laboratory for further testing.
Magnetic Resonance Imaging (MRI) Scan: The doctor may advise a brain MRI scan to check the pituitary gland for any tumors and to denote its size and exact location. A healthcare professional will ask the patient to lie down on the bed of the machine. Once the patient is settled, the expert will operate the machine from a different chamber. Several scans are taken to get a clear picture of the tumor, which takes around half an hour to complete. The sound of the machine will be very loud and high-pitched, so earplugs are given.
What Are the Treatment Options for Thyrotropinoma?
Treatment options include:
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Surgical Method: Surgery is the primary treatment for thyrotropinoma. A minimally invasive surgical method known as transsphenoidal surgery is done to remove the pituitary tumor. A small cut is made inside the nose, and the sphenoid sinus wall is opened using a small instrument. The instrument is passed through the opening to remove the tumor. The tumor is easily visible with the help of an endoscope (a thin fiber-optic tube with a camera). It is a very safe procedure as no part of the brain is touched, and there are no scars after the surgery.
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Radiation Therapy: It is advised for several reasons. In case of successful surgery, radiation therapy is done to avoid the recurrence of the tumor. In some cases where surgery can not be performed, radiation therapy is done to destroy the tumor. The radiation therapy technique called stereotactic radiosurgery is generally done. This high-frequency radiation beam targets the tumor and does not harm the surrounding area of the brain. A frequent follow-up, even after the completion of radiation therapy, is beneficial as it helps monitor any growth or changes in the tumor.
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Medication: Anti-thyroid medications such as beta-blockers (for high blood pressure and rapid pulse rate) and Methimazole can be given, but they take weeks to become effective.
Conclusion
Thyrotropinoma, or TSHoma, is a tumor in the thyrotropic cells of the pituitary gland. It is left undiagnosed in very few cases for many years due to no visible symptoms. However, it may show symptoms like rapid heartbeat and tremors in most cases. Such symptoms should be acknowledged and informed to the doctor. A blood test is one of the diagnostic methods that help in confirming the condition. Thyrotropinoma can be easily treated through surgery and does not cause recurrence in most cases. Still, even after successful surgery, a regular doctor visit helps track overall health.
