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Pituitary Galactorrea


Drug-Induced Galactorrhea

  • Definition: Galactorrhea is the production of breast milk in men or in women who are not breastfeeding. Drug-induced galactorrhea occurs when certain medications lead to an increase in prolactin levels, causing milk secretion.

  • Mechanism: These drugs typically interfere with dopamine action, which normally inhibits prolactin secretion. Without this inhibition, prolactin levels rise, potentially leading to galactorrhea.

Common Medications Causing Galactorrhea

  1. Antipsychotics: Medications like risperidone and haloperidol can increase prolactin levels.

  2. Antidepressants: Especially SSRIs and tricyclics.

  3. Anti-hypertensives: Such as verapamil and methyldopa.

  4. Gastrointestinal drugs: Like metoclopramide, a dopamine antagonist used for nausea.

Drug-Induced Galactorrhea: Mechanisms and Associated Drugs

Dopamine-Receptor Blockade

  • Metoclopramide: A dopamine receptor antagonist that is commonly used for gastrointestinal issues, which can increase prolactin levels.

  • Phenothiazines: A class of antipsychotic drugs that can cause hyperprolactinemia by blocking dopamine receptors.

  • Risperidone: An antipsychotic medication that can increase prolactin levels by antagonizing dopamine receptors.

  • SSRIs (e.g., Fluoxetine, Sertraline): While SSRIs primarily increase serotonin levels, they can also influence dopamine systems and lead to elevated prolactin levels.

  • Tricyclic Antidepressants: These can increase prolactin levels by antagonizing dopamine receptors.

Dopamine-Depleting Agents

  • Reserpine: Used to treat hypertension and some psychotic conditions by depleting dopamine stores.

  • Methyldopa: An antihypertensive medication that can deplete dopamine and elevate prolactin levels.

Inhibition of Dopamine Release

  • Heroin: An opioid that can inhibit dopamine release, potentially leading to increased prolactin levels.

  • Morphine: Another opioid that can inhibit the release of dopamine and cause elevated prolactin.

Histamine-Receptor Blockade

  • Cimetidine: A histamine H2-receptor antagonist that can cause an increase in prolactin levels, potentially leading to galactorrhea.

Stimulation of Lactotrophs

  • Oral Contraceptives: Contain estrogen which can stimulate lactotroph cells in the pituitary gland, increasing the production of prolactin.

  • Verapamil: A calcium channel blocker used to treat hypertension, which can also stimulate prolactin release, although the mechanism may be multifaceted.

Management

For the management of drug-induced galactorrhea, the slide suggests stopping the implicated medication for 3 days, if medically safe to do so, to observe for a decrease in symptoms.



Prolactinoma

  • Definition: A prolactinoma is a benign tumor of the pituitary gland that produces an excessive amount of prolactin.

  • Diagnosis:

  • Exclude other causes of hyperprolactinemia.

  • Serum prolactin levels: Levels >200 ng/ml suggest a prolactinoma (excluding drugs like risperidone and metoclopramide). Levels >500 ng/ml indicate a macroprolactinoma.


Case Secondary amenorrhea

Thyroid Function Tests (TFTs):

  • Regulation of Menstrual Cycle:

  • The menstrual cycle is regulated by a complex interplay of hormones, including those produced by the thyroid gland.

  • Thyroid hormones interact with reproductive hormones. For instance, thyroxine (T4) and triiodothyronine (T3) can influence the levels of sex hormone-binding globulin (SHBG), affecting the availability of estrogen and other sex hormones.

  • Impact on Ovulation:

  • Normal thyroid function is essential for ovulation. Both excess and insufficient thyroid hormones can disrupt the hypothalamic-pituitary-ovarian axis.

  • In hypothyroidism, elevated Thyroid Stimulating Hormone (TSH) levels can lead to increased prolactin, interfering with the release of FSH and LH, which are critical for follicle development and ovulation.

  • Hyperthyroidism may cause menstrual irregularities by speeding up the body's overall metabolism, which can disrupt the menstrual cycle's regular rhythm.

  • Clinical Implications:

  • It's not just the presence of menstrual irregularities but also their pattern that can hint at thyroid involvement. For example, menorrhagia (heavy menstrual bleeding) is more common in hypothyroidism.

Renal Function Tests:

Prolactin Level:




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