Macroprolactinoma is a type of pituitary tumor that leads to excess production of the hormone prolactin. This type of tumor is larger than a microprolactinoma but smaller than a giant prolactinoma.
Your pituitary gland is a pea-size gland found at the base of your brain that secretes many hormones. Tumors on your pituitary gland can lead to the overproduction of those hormones. Additionally, large tumors can press on surrounding structures in your brain and cause other problems.
Tumors that secrete prolactin are known as prolactinomas. Prolactin is a hormone that’s responsible for triggering breast tissue development and milk production. It also influences testicular function.
Large prolactinomas are called macroprolactinomas. They’re often manageable with medications but sometimes require surgery or radiation therapy.
Read on to learn more about macroprolactinomas, including why they form and how they’re managed.
Macroprolactinoma vs. microprolactinoma and giant prolactinomas
Macroprolactinomas, microprolactinomas, and giant prolactinomas are all tumors on your pituitary gland that cause prolactin overproduction. They’re all considered types of prolactinoma, but they’re classified according to their size, as shown below. The sizes are given in millimeters (mm), inches (in), and centimeters (cm).
| Tumor type | Size |
|---|---|
| microprolactinoma | smaller than 10 mm (0.4 in) |
| macroprolactinoma | larger than 10 mm (0.4 in) |
| giant prolactinoma | larger than 4 cm (1.6 in) |
Most prolactinomas develop without a known cause. These are known as spontaneous tumors.
In some cases, prolactinomas are linked to certain inherited conditions that run in families, such as multiple endocrine neoplasia type 1 (MEN1). An estimated
Prolactinomas make up
From 25 to 44 years of age, females are about
Macroprolactinomas make up about 10% of all prolactinomas but about 80% of prolactinomas in males.
- in females:
- changes in menstruation
- milky nipple discharge
- low sex drive
- pain during sex
- vaginal dryness
- infertility
- in males:
- erectile dysfunction
- low sex drive
- infertility
Females often seek medical attention sooner than males since their symptoms might become more apparent earlier. This may be why macroprolactinomas make up a larger percentage of prolactinomas in males.
Having excess prolactin in your body can cause problems such as infertility and bone loss, which can lead to osteoporosis.
Some people with prolactinomas have deficiencies of
- growth hormone
- thyroid-stimulating hormone
- adrenocorticotrophic hormone
Macroprolactinomas can press against structures near your pituitary gland, such as the optic nerve or optic chiasm, potentially leading to vision problems.
Some people may also have headaches or seizures.
Medications used to treat prolactinomas have been linked to heart valve problems.
The early symptoms of a prolactinoma can be subtle. Symptoms might worsen over time as the tumor grows. It’s important to consult a doctor if you think you may have a hormonal issue without an obvious cause.
Atypical lactation and low sex drive are potential warning signs of prolactinomas.
The diagnostic process for macroprolactinoma usually starts with a visit to a primary healthcare professional. They will likely:
- consider your symptoms
- perform a physical exam
- review your personal and family medical history.
A blood test is the primary way that healthcare professionals discover a macroprolactinoma. Not everyone who has high prolactin levels will have a tumor, but if your levels are high, your doctor will likely order imaging to check for a tumor.
The
Macroprolactinomas require
Oral medications called dopamine agonists are the main treatment for prolactinomas. According to older research cited in a 2018 case report, dopamine agonists are effective at normalizing prolactin levels in 66% to 100% of cases and at shrinking the tumor in 64% to 96% of cases.
If these drugs are not effective, you may need surgery or radiation therapy. Surgery can often be performed with a minimally invasive technique called transsphenoidal surgery.
Most macroprolactinomas develop without a known cause. There’s no known way to prevent them, but a doctor may recommend regular monitoring if you have a family history of MEN1.
Is macroprolactinoma cancer?
Most prolactinomas are
What does it mean when prolactin is high?
High prolactin can be a sign of a tumor on your pituitary gland. It can also be caused by some medications and some other underlying health conditions.
Macroprolactinomas are large tumors on your pituitary gland that cause overproduction of the hormone prolactin. In females, high prolactin might cause irregular menstruation or loss of sex drive. In males, it may cause loss of sex drive or infertility.
Most macroprolactinomas can be treated with medications called dopamine agonists, which lower your prolactin levels. Tumors that don’t respond to these medications may require surgery or radiation therapy.