Prolactinoma

These include hormone panels that check for abnormalities in growth hormone, cortisol, and thyroid-stimulating hormone, as well as elevated prolactin. Consistently high prolactin levels suggest the presence of this type of tumor.

Imaging tests, especially magnetic resonance imaging (MRI), provide a detailed view of the pituitary gland and surrounding areas. A pituitary MRI is performed with and without Gadolinium to detect the size and exact location of the tumor. In some cases, if MRI is unavailable, a computed tomography (CT) scan may also help.

Since larger pituitary tumors can press on nearby optic nerves, doctors may recommend vision testing to evaluate any impact on sight.

• A prolactin level of over 150-200 ng/ml is almost always due to a prolactinoma.
• Moderate prolactin elevations (30-200 ng/ml) can occur from other causes such as pregnancy, stress (discomfort, exercise), low thyroid function (hypothyroidism), kidney or liver failure and medications (e.g., haloperidol, antidepressants, verapamil).
• An additional cause of high prolactin level is “stalk compression effect” from a pituitary or brain tumor that compresses the pituitary stalk.
• Other adenomas, craniopharyngiomas, Rathke’s cleft cysts and other brain tumors may cause modest prolactin in the range of 40 – 150 ng/ml.
• In cases of macroprolactinomas, these larger tumors in addition to hypogonadism, may cause other pituitary hormonal deficiencies from gland compression (such as low thyroid or cortisol hormones), headaches or visual loss (from adenoma compression of the optic nerves or optic chiasm).
• Some larger prolactinomas are diagnosed when they hemorrhage (bleed), also known as pituitary apoplexy.

In general, first line treatment for patients with a prolactinoma is medication rather than endonasal surgery.

Approximately 80-85% of patients will have prolactin levels restored to normal with dopamine agonist therapy and many will have marked tumor shrinkage. The most commonly used agent is cabergoline (Dostinex) which has replaced bromocriptine (Parlodel) as the drug of choice given cabergoline’s higher success rate and lower side-effect rate. Most women, following treatment, have a return of menses and many become fertile again. Tumor shrinkage occurs in the majority of patients, which often results in rapidly improved vision and headache resolution.

Dostinex has the advantage of only being taken twice per week and has fewer side effects than bromocriptine. It has also been shown effective in patients whose prolactinomas are resistant to bromocriptine therapy. The usual starting dose is 0.5 mg twice per week. The dose may be increased up to 1.0 mg twice per week.

Bromocriptine is used infrequently now for prolactinomas given the higher rate of side-effects and is usually started at a low dose (2.5 mg/day) to minimize nausea and other side effects. The dose is then increased over several days or weeks to a daily maximum usually not over 10 mgs.

Recent reports indicate long-term high-dose therapy with cabergoline or bromocriptine can result in valvular heart disease. Although this risk is relatively low with standard doses of cabergoline and bromocriptine used to treat a prolactinoma, it remains a potential risk of this therapy.

Surgery is a reasonable first-line therapy in patients with microprolactinomas that do not invade the cavernous sinus and whose prolactin level is less than 250 ng/ml. In these patients, long term remission is generally 80-90%. Endonasal surgery is also effective for lowering prolactin levels in patients intolerant of cabergoline.

For invasive microprolactinomas with prolactin levels over 1000 ng/ml, the surgical cure rate is low, averaging less than 30%. For this reason, cabergoline is usually tried first.

In patients with long-standing visual loss from tumor compression, cabergoline can be tried first. However, if visual loss has occurred rapidly over a period of several days or weeks, or if there is evidence on MRI of subacute hemorrhage or degeneration in the tumor, endonasal surgery for tumor debulking is generally recommended.

Because of improved tumor visualization, the endoscopic endonasal approach has become the preferred method for removal of most pituitary adenomas, including prolactinomas that are not responsive to cabergoline.

Due to major technological advances including use of high-definition endoscopy and surgical navigation techniques, endoscopic transsphenoidal surgery is a minimally invasive, effective approach.

Because most patients with prolactinomas respond so well to dopamine agonist therapy and/or surgery, radiosurgery or radiation therapy are rarely required.

Most patients have an excellent prognosis with treatment. Medication is effective for the majority, and surgery can provide lasting remission in many cases. Ongoing monitoring is important to detect any recurrence early.

While benign, a prolactinoma can cause significant symptoms and complications if untreated, including vision loss, infertility, and hormonal imbalances. With treatment, it is usually very manageable.

Most occur sporadically without a clear cause, though a small number are linked to genetic conditions such as MEN1.

Treatment typically starts with medication (cabergoline or bromocriptine). Surgery is considered for medication intolerance, resistance, or urgent vision-threatening situations.

Life expectancy is generally normal for people with benign pituitary tumors, including prolactinomas, provided they receive appropriate treatment and follow-up.

Symptoms may include fatigue, reduced sex drive, weight gain, headaches, vision problems, and — in women — menstrual changes and lactation.

Avoid medications that increase prolactin unless approved by your doctor. It’s also important to avoid missing doses of prescribed treatment and skipping follow-up appointments.