Anterior Pituitary Hormones

Physiology of the Anterior Pituitary

• The anterior pituitary secretes several key hormones regulated by hypothalamic-releasing and inhibiting factors.

Hormones Produced:

• Growth Hormone (GH)

• Prolactin

• Thyroid-Stimulating Hormone (TSH)

• Adrenocorticotropic Hormone (ACTH)

• Luteinizing Hormone (LH)

• Follicle-Stimulating Hormone (FSH)

Regulation:

• Stimulation: Releasing factors such as GHRH stimulate GH secretion.

• Inhibition: Inhibitory factors like somatostatin suppress GH release.

Key Anterior Pituitary Hormones

Classification of Anterior Pituitary

1) Growth Hormone (GH) and Its Analogues

• Somatropin (Recombinant GH):

  • Uses: GH deficiency (children/adults), Turner syndrome, chronic kidney disease.

  • Adverse Effects: Edema, arthralgia, hyperglycemia.

• Mecasermin (Recombinant IGF-1):

  • Uses: GH insensitivity in children.

  • Adverse Effects: Hypoglycemia (monitor glucose).

2) GH Inhibitors (Somatostatin Analogues):

• Octreotide, Lanreotide:

  • Mechanism: Mimic somatostatin to inhibit GH, TSH, glucagon, and insulin.

  • Uses: Acromegaly, secretory diarrhea (e.g., VIPomas), variceal bleeding.

  • Adverse Effects: GI disturbances, gallstones, bradycardia.

3) Prolactin and Its Inhibitors

• Dopamine Agonists (Bromocriptine, Cabergoline):

  • Mechanism: Suppress prolactin secretion.

  • Uses: Hyperprolactinemia (galactorrhea, infertility), prolactin-secreting adenomas, Parkinson’s disease.

  • Adverse Effects: Nausea, headache, orthostatic hypotension, psychiatric disturbances.

4) Other Anterior Pituitary Hormones

• Adrenocorticotropic Hormone (ACTH):

  • Analogues: Synthetic ACTH (cosyntropin) for adrenal insufficiency testing.

  • Inhibitors: Indirectly inhibited by glucocorticoids via negative feedback.

• Thyroid-Stimulating Hormone (TSH):

  • Analogues/Inhibitors: Direct pharmacological agents are less common; instead, thyroid hormone analogues or antithyroid drugs indirectly influence TSH levels via feedback.

• Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH):

  • Analogues: GnRH analogues (e.g., leuprolide) for prostate cancer, fertility treatments.

  • Inhibitors: GnRH antagonists (e.g., degarelix) suppress LH and FSH quickly.