Small gland, big impact: Functional and nonfunctional pituitary tumors
The pituitary gland is a tiny organ, only about the size of a pea, located at the base of your brain. I think of the pituitary gland like the conductor of a mighty orchestra. As part of the endocrine system, the pituitary gland produces many hormones that travel throughout the body and direct other glands to work. Ordinarily, it’s a great system—unless that conductor starts misdirecting the orchestra, which can happen if you have a pituitary tumor.
Pituitary tumors usually aren’t cancerous, but that doesn’t mean they don’t require treatment. When we know which types of tumors we’re dealing with and how they behave, we’re better able to treat them. We classify pituitary tumors as either functional or nonfunctional.
Listen: Dr. Sharma discusses functional and nonfunctional pituitary tumors on the Medical Intel podcast.
Differences between functional and nonfunctional pituitary tumors
The classification of a pituitary tumor depends on whether it produces too much of a hormone normally produced by your pituitary gland. The pituitary gland produces hormones to regulate many systems in your body, including:
- Adrenocorticotropic hormone (ACTH), which acts on the adrenal glands to stimulate the production of cortisol, which helps regulate the metabolism, heart rate, blood pressure and muscle tension
- Growth hormone (GH), which controls the body’s normal growth process, particularly in children during puberty
- Luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which affect the reproductive glands of men and women
- Prolactin, which promotes milk production in pregnant and nursing mothers
- Thyroid-stimulating hormone (TSH), which acts on the thyroid gland to make thyroid hormones
Pituitary tumors that produce excess hormones are called functional pituitary tumors. Those that don’t are called nonfunctional pituitary tumors. Nonfunctional tumors can cause a decrease in normal hormone production. These tumors can compress the pituitary gland and reduce the amount of hormones it’s able to release.
How we diagnose pituitary tumors
On occasion, we detect pituitary tumors during a test for other conditions, such as a magnetic resonance imaging (MRI) scan for a patient who has headaches that might not be related to a pituitary tumor. Many times, however, the process starts with an exam.
We may test for a particular hormone if we see a patient with obvious signs of a functional pituitary tumor. If the symptoms aren’t as obvious, we may need to test for all pituitary hormones. Symptoms we look for include:
- Breast milk production in a woman who is not pregnant or has not had a baby recently, which is a sign of too much prolactin
- Distortion of facial features and/or abnormal growth of hands and feet (known as acromegaly), which can indicate too much GH
- Hyperthyroidism, or an overactive thyroid gland, a possible sign of too much TSH
- Rapid weight gain and fat buildup in the body, particularly on the back of the neck, can be caused by too much ACTH and can indicate Cushing’s disease
Blood and urine tests can tell us whether you have too much or not enough of a particular type of hormone. After that, we move on to dynamic blood testing, which involves the collection of blood samples over a several-hour period so we can measure changes in hormone levels.
Next, we need to get detailed images of the pituitary gland, so we can be sure whether you have a tumor, where it’s located and how large it is. These images may come from:
- MRI (preferred)
- Computed tomography (CT)
- Positron emission tomography (PET)
If you have a pituitary tumor, we need to make sure it’s not causing vision loss. Because nonfunctional tumors often don’t cause symptoms that patients notice, they might grow large enough to compress other areas of the brain, such as the optic nerve. This nerve transmits images from the eye to the brain. A large nonfunctional pituitary tumor can press on the optic nerve’s fibers, leading to loss of peripheral vision, or can invade the blood spaces surrounding the pituitary tumor (cavernous sinuses), occasionally affecting the nerves controlling eye movements, leading to double vision.
A nonfunctional pituitary tumor might not need to be removed right away, depending on its size and location, as well as any symptoms you may have. A functional tumor, however, always needs treatment because of its effects on your body’s hormones.
How we treat pituitary tumors
If you have a prolactin-secreting pituitary tumor, we usually can treat it with medications. Medications for prolactin-secreting tumors are so effective that we can shrink a tumor and bring the hormone levels under control without surgery.
Most other pituitary tumors need to be removed surgically, so it’s important for your treatment team to include an expert neurosurgeon. Your neurosurgeon likely will be able to remove your tumor through a minimally invasive technique, which can offer faster recovery times than traditional pituitary surgery, along with no visible scarring. We’re fortunate to have Dr. Edward F. Aulisi, one of the country’s leading experts in pituitary surgery, overseeing our neurosurgery team.
Our surgical treatments for pituitary tumors include:
- Transsphenoidal surgery: The neurosurgeon makes a small incision in your nose or under your upper lip to remove the tumor through the sphenoid sinus, which is behind your nasal passages. We remove most pituitary tumors with this method.
- Craniotomy: The neurosurgeon makes incisions on the front and side of your skull to remove the tumor. This procedure typically is for pituitary tumors that are too large or complex to access through minimally invasive techniques.
The improvements we see after the removal of a pituitary tumor can be extraordinary. For example, I saw one patient who was in her 50s and, other than her well-controlled diabetes, had previously been perfectly healthy. Then she gained a lot of weight, and her muscles became so weak that she first needed a wheelchair, then couldn’t get out of bed at all. Her diabetes progressed out of control, and she developed high blood pressure and dangerous blood clots. We detected an ACTH-secreting pituitary tumor that had caused her to develop Cushing’s disease and led to her many health issues. After the patient’s tumor was removed and her hormone levels went back to normal, she started to recover. Now, after a year of intensive physical therapy, this patient is able to walk again, she no longer has high blood pressure and her diabetes is back under control. It’s a remarkable turnaround, and it’s just one of many such stories I’ve seen unfold after successful treatment for pituitary tumors.
The pituitary gland may be little, but it’s critical to your body’s normal function. Through our team-based approach of identification and treatment, I’m confident that we can help more patients overcome these tumors and live a healthy life.
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