A TSH-producing pituitary adenoma is one that makes too much of the hormone called “thyroid stimulating hormone.” Thyroid stimulating hormone stimulates the thyroid gland to produce the thyroid hormones (T4 and T3). These hormones regulate metabolism and affect the growth and rate of function of other organs. Continuous stimulation of the thyroid gland by TSH may cause an overactive thyroid gland (hyperthyroidism).
About TSH-Producing Adenomas
A TSH-producing pituitary adenoma is the least common type of pituitary adenoma, occurring in only 1-3 percent of all pituitary adenomas. This type of tumor is more common in females. The tumors are often greater than 1 cm in diameter, referred to as a macroadenoma.
Since this type of tumor affects multiple areas of the body, a team that includes an endocrinologist, a neurosurgeon, an ophthalmologist and a radiologist need to treat this tumor together.
With successful treatment, hormone levels can return to normal and the tumor can be removed.
Symptoms of hyperthyroidism include:
- Weight loss
- A fast heartbeat (palpitations)
- Tremor of the hands
- Difficulty sleeping
- Frequent bowel movements
- Less menstrual flow or loss of menstrual periods
Other symptoms of pituitary tumors are:
- Visual loss
There are no known steps to prevent TSH-producing adenomas but early diagnosis improves the chance of cure with surgery alone
A diagnosis is confirmed by:
- TSH and the thyroid hormone levels (T4 and T3) blood tests: In general, elevated T3 and/or T4 in the presence of normal or elevated TSH suggests a TSH-producing tumor. In some cases, thyroid hormones are normal despite the presence of a tumor. This is called a “silent TSH adenoma.”
- Imaging the pituitary by MRI or CT: Presence of a pituitary adenoma on the MRI study usually shows a large tumor; however, some tumors may be too small to see.
Early treatment prevents the progression of visual loss and headaches caused by many larger tumors.
The goals of treatment are to:
- Restore production of TSH and thyroid hormones to normal
- Stop and reverse the symptoms of TSH-producing adenomas
- Correct other endocrine abnormalities (adrenal, ovaries or testes)
- Remove and/or destroy the tumor to restore endocrine function to normal and to relieve any symptoms directly related to the tumor (headaches, visual disturbance)
Medical treatment for this type of tumor is a somatostatin analog, Sandostatin LAR. This drug acts on the tumor to lower TSH production by the tumor, which results in lowering of both TSH and thyroid hormone levels.
Some patients have a decrease in tumor size as well. Some patients have been treated successfully only with Sandostatin LAR (an injection in the buttock once a month) and have not required surgery. Sandostatin LAR does not destroy the tumor; it is only effective as long as it is administered, so it is not a cure.
Surgery is the most common treatment for TSH-producing adenomas, and is done using a transphenoidal approach (the operation is performed through the nose without disturbing the brain or the eye nerves).
In order to protect against heart problems (abnormal heart rhythm) during surgery, TSH-producing tumors require treatment fore surgery. This treatment usually takes 3–4 weeks. The medications used include a “beta-blocker” like propranolol or metroprolol, which slows the heart rate, and methimazole, a drug that reduces the amount of thyroid hormone production.
After Successful Surgery
Once the tumor is completely removed, normal thyroid hormone production resumes. Although hormone levels will return to normal within days, the symptoms of a TSH-producing adenoma may take days to weeks to resolve.
Some patients may have very loe TSH levels after surgery. These patients may need thyroid hormone replacement either temporarily or permanently.
Radiation therapy or radiosurgery are options for patients who have persistent elevation of TSH despite medical therapy or patients who can’t receive medical therapy for one reason or another. Conventional radiation therapy is effective, but does involve a 4-6 week period of treatment. A single treatment with Gamma Knife has been a successful option and has the potential of providing excellent long-term control.
Your pituitary tumar may recur at any time, so you’ll need regular follow up visits with blood tests and, if the blood tests show a return of high TSH and thyroid hormone levels, an MRI. You’ll need additional treatment if your tumor recurs.
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Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.