Pituitary Gland Hormones
The pituitary gland regulates seven primary hormones: from the anterior pituitary—thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), prolactin, growth hormone (GH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH); and from the posterior pituitary—oxytocin and vasopressin (antidiuretic hormone). 1
Anterior Pituitary Hormones
The anterior pituitary system secretes five major hormones under the influence of hypothalamic trophic factors 1:
- Thyroid-Stimulating Hormone (TSH): Regulates thyroid gland function and metabolism
- Adrenocorticotropic Hormone (ACTH): Controls adrenal cortex function and stress response 2
- Prolactin: Primarily regulates lactation 2
- Growth Hormone (GH): Controls post-natal growth, fat metabolism, and glucose utilization 3
- Gonadotropins (LH and FSH): Regulate reproductive function and gonadal activity 2
These hormones are secreted by distinct cell types within the anterior pituitary: thyrotropes (TSH), corticotropes (ACTH), lactotropes (prolactin), somatotropes (GH), and gonadotropes (LH/FSH) 4, 5.
Posterior Pituitary Hormones
The posterior pituitary consists of axonal terminations from neurons whose cell bodies are located in the hypothalamus 1. It secretes:
- Oxytocin: Regulates uterine contractions and milk ejection 5, 6
- Vasopressin (Antidiuretic Hormone/ADH): Controls water balance, blood pressure, and prevents excessive urination 2, 5
Clinical Significance
The hypothalamic-pituitary axis functions as a critical regulatory system where the hypothalamus produces releasing and inhibiting factors that control anterior pituitary hormone secretion through the portal vascular system 1, 7, 5. This integrated system maintains homeostasis by regulating peripheral endocrine organs including the thyroid, adrenal glands, and gonads 4, 6.
When evaluating pituitary function clinically, all hormonal axes must be assessed 8, 9. For suspected pituitary dysfunction, baseline screening should measure free thyroxine (T4), TSH, morning cortisol, ACTH, LH, FSH, and IGF-1 levels, with testosterone in men and estradiol in women as needed 8. Prolactin and IGF-1 should be measured in all patients with incidentally discovered pituitary lesions to screen for hormone hypersecretion 8.