🧬 Prolactin – The Basics
- A hormone that affects reproduction, breastfeeding, and metabolism.
- Made in the anterior pituitary gland by lactotroph cells.
- Dopamine controls prolactin by acting as a "brake" to stop excessive release.
🤰 Prolactin in Pregnancy & Breastfeeding
- Increases 10x during pregnancy due to higher estrogen levels.
- Prepares the body for milk production.
- Returns to normal within 6 months after birth.
🔄 How is Prolactin Controlled?
- Dopamine reduces prolactin levels.
- Some factors increase prolactin, such as:
- Thyrotropin-releasing hormone (TRH)
- Serotonin
- Certain peptides & neuroactive chemicals
🏗️ Types of Prolactin
- Monomeric prolactin (80–90%) – Most active form.
- Dimeric prolactin (8–20%) – Less active.
- Macroprolactin (1–5%) – Inactive form.
🚫 Effects of High Prolactin (Hyperprolactinemia)
- Can stop ovulation, causing irregular periods or infertility.
- Reduces LH, affecting egg release.
- Lowers progesterone, making pregnancy difficult.
- In some cases, ovulation still happens but hormone balance is disturbed.
👶 Prolactin & Female Infertility
- Can stop ovulation, leading to irregular or absent periods.
- PCOS patients often have high prolactin & LH, but the connection is unclear.
- Dopamine agonists restore ovulation in 90% of cases, with 80–85% pregnancy success.
- In some ovulating women, slightly high prolactin may reduce fertility, but evidence is mixed.
- Macroprolactin is inactive and does not cause infertility.
🔎 Should You Test Prolactin for Infertility?
- Not recommended unless:
✅ Ovulation problems exist.
✅ Milk discharge (galactorrhea) is present.
✅ A pituitary tumor is suspected.
- Mildly high prolactin does not always affect pregnancy chances.
🤰 Prolactin & Miscarriage Risk
- A study showed reducing high prolactin with bromocriptine increased pregnancy success in women with past miscarriages.
- More research is needed to confirm its role in pregnancy loss.
FOR TOACS STUDENTS START FROM HERE
🩺 Assessment of a Subfertile Woman with Hyperprolactinaemia
🔍 1. Clinical Evaluation
- A detailed medical history is necessary to rule out physiological or secondary causes of high prolactin levels.
- Medications should be reviewed, as some drugs can cause elevated prolactin.
🔬 2. Confirming the Diagnosis
- Repeat prolactin testing is needed to ensure the raised levels are consistent before proceeding with further investigations.
- Macroprolactin assessment is important to rule out biologically inactive prolactin, which does not require treatment.
⚠️ 3. Beware of False Readings (Hook Effect)
- In cases of macroadenomas (large pituitary tumors), extremely high prolactin levels can interfere with lab tests.
- This can lead to falsely low readings due to the "hook effect", where excess prolactin saturates antibodies in the assay.
- To avoid misdiagnosis, prolactin should be measured in both undiluted and diluted serum samples.
🔄 4. Differentiating Causes of Hyperprolactinaemia
- Disconnection hyperprolactinaemia:
- Caused by non-functioning pituitary tumors, which block dopamine inhibition and lead to increased prolactin.
- Prolactin levels usually stay below 2000 mIU/l.
- Prolactin-secreting adenomas (Prolactinomas):
- Tumors that actively produce prolactin, leading to very high levels (>2000 mIU/l).
- This distinction is crucial, as prolactinomas respond to medical treatment, while disconnection hyperprolactinaemia does not.
🧪 5. Checking Other Hormones
- Thyroid function tests (TSH ) should be done, as hypothyroidism can cause high prolactin levels by directly stimulating lactotrophs.
🧲 6. Pituitary MRI for Tumor Detection
- MRI is the best imaging test to detect pituitary adenomas.
- Prolactinomas classification:
- Microadenomas (<10 mm in size).
- Macroadenomas (>10 mm in size).
- Studies show that 10% of healthy people may have small, non-functioning pituitary tumors without symptoms.
⚖️ 7. When is MRI Needed?
- MRI is recommended before starting treatment to avoid misdiagnosing or underdiagnosing microprolactinomas.
- If prolactin levels are <1000 mIU/l and no other symptoms of pituitary disease are present, MRI may not be necessary.
🏥 Management of Prolactin Excess
📌 When is Treatment Needed?
🔹 Due to High Prolactin Effects:
- Infertility & Anovulation (irregular or absent ovulation).
- Reduced Bone Density (risk of osteoporosis).
- Galactorrhoea (unexpected milk production).
🔹 Due to Tumor Pressure (Mass Effect):
- Vision problems (pressure on the optic nerve).
- Pituitary dysfunction (hormonal imbalance).
- Nerve problems & headaches (cranial nerve compression).
💊 Medical Treatment (First-Line Therapy)
🟢 Dopamine Agonists
The most effective medications for reducing prolactin levels and shrinking tumors.
1️⃣ Bromocriptine
✅ Effective for 80–90% of women (restores ovulation).
✅ Reduces tumor size in 70% of cases.
✅ Improves vision problems & headaches quickly.
❌ Side Effects:
- Nausea (30%), vomiting (20%), dizziness (25%).
- Must be taken 1–3 times daily due to a short half-life.
✔ Safe in pregnancy with long-term safety data.
2️⃣ Cabergoline
✅ More effective than bromocriptine with fewer side effects.
✅ Ovulation resumes in 95% and tumor size decreases in 80%.
✅ Taken once or twice a week (longer half-life).
❌ Risk of heart valve problems at very high doses.
🔍 Monitoring:
- Echocardiography every 6–12 months if taking high doses.
✔ No evidence of harm in pregnancy, but less safety data available.
3️⃣ Quinagolide (Non-Ergot Derived)
✅ Similar effectiveness to bromocriptine.
✅ Fewer side effects than bromocriptine.
✅ Once-daily dosing (long half-life).
✔ Lower risk of heart valve problems (non-ergot).
❌ Limited pregnancy safety data, but no birth defects reported.
🏥 Surgical Treatment
Used only when medication fails or is not suitable.
🔹 When is Surgery Needed?
- Failure of medication to control prolactin levels.
- Growing tumors causing vision or nerve problems.
- Pituitary apoplexy (sudden bleeding into the tumor, leading to headaches, vision loss, or collapse).
🔹 Surgical Procedure:
- Transsphenoidal Surgery (through the nose) – preferred method.
- Craniotomy (through the skull) – used for large or inaccessible tumors.
✔ Success Rates:
- 74–75% for small tumors (microprolactinomas).
- 34–38% for large tumors (macroprolactinomas).
🎯 Radiotherapy (Last Resort Treatment)
Used only when medications and surgery fail.
❌ Risks of Radiotherapy:
- Hormone deficiencies (70%).
- Brain tissue damage (<1%).
- Cranial nerve or optic nerve damage (1%).
- Rare cases of secondary brain tumors.
🤰 Hyperprolactinaemia & Pregnancy
Treatment for Women Trying to Conceive
- Women Trying to Conceive (Pre-Pregnancy counselling )
🤰 Antenatal Care (ANC) – Managing Hyperprolactinemia in Pregnancy
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- Medical treatment is the first choice (Bromocriptine or Cabergoline).
- Surgery may be needed if the tumor is large and has a cystic component that does not respond to medication.
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During Pregnancy – What to Expect?
- Microprolactinomas (Small Tumors):
✅ Low risk of growth (~2.6%).
✅ Most women do not need medication during pregnancy.
- Macroprolactinomas (Large Tumors):
❌ Higher risk of growth (30–35%), causing vision problems or headaches.
✅ May require continued medication during pregnancy.
✅ MRI is done if symptoms appear (e.g., vision changes).
-
Routine ANC Follow-Up:
✅ Monitor prolactin levels if needed (not always necessary).
✅ Monitor vision changes (risk of tumor growth).
✅ MRI if symptoms worsen (only if medically necessary).
🏩 Intrapartum (During Delivery) Care
- Aim vaginal delivery at term
🤱 Postpartum Considerations
-
Breastfeeding & Prolactin Levels:
✅ Prolactin naturally increases for breastfeeding.
✅ If the mother wants to breastfeed, medications may not be needed immediately.
✅ If milk production is excessive after stopping breastfeeding, dopamine agonists can be restarted.
-
Tumor Monitoring After Delivery:
✅ Prolactin levels usually return to normal.
✅ MRI follow-up if symptoms persist postpartum.
✅ If vision problems or severe headaches occur, seek urgent medical attention.
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