Hypopituitarism

• The anterior lobe of the pituitary gland is responsible for synthesizing and releasing several essential hormones, including growth hormone (GH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicular-stimulating hormone (FSH), adrenocorticotropin hormone (ACTH), and prolactin (PRL)
• The posterior pituitary lobe is responsible for storing and releasing 2 essential hormones, including oxytocin and antidiuretic hormone (ADH), which is also called vasopressin. These hormones are synthesized by neurosecretory cells located in the hypothalamus.
• Hypopituitarism is a medical condition characterized by a deficiency in 1 or more of the hormones produced by the pituitary gland. This condition is associated with an increased mortality risk from cardiovascular and respiratory diseases.
• Hypopituitarism can originate from 2 primary sources—pathology of the hypothalamus, which affects the production of tropic hormones that act on the pituitary, or direct pathology within the pituitary gland itself.
• The predominant cause of hypopituitarism is pituitary tumours. These tumors may cause overproduction of a single hormone, leading to a deficiency in other pituitary hormones.
•  In addition to tumors, various injuries to the pituitary gland, such as traumatic brain injury, iatrogenic injury during surgery, or cranial irradiation, may also cause hypopituitarism.
• Effects:

  • ACTH deficiency: ACTH deficiency results in adrenal insufficiency.
  • TSH deficiency: TSH deficiency leads to hypothyroidism.
  • Gonadotropin deficiency: Gonadotropin deficiency leads to hypogonadism.
  • GH deficiency: GH deficiency in children can result in poor growth and short stature. Although this hormonal deficiency is typically asymptomatic in adults, some individuals may experience fatigue and weakness.
  • ADH deficiency: ADH deficiency leads to diabetes insipidus, characterized by symptoms such as polydipsia and polyuria.
• Symptoms:

  • Hypothyroidism: small and soft thyroid gland, dry and coarse skin, hair thinning and alopecia, delayed tendon reflexes, cold skin with reduced sweating, and non-pitting edema.
  • Adrenal insufficiency: fatigue and postural hypotension.
  • Hypogonadism: In men, this condition can manifest as small and atrophied testes, whereas in women, it may lead to the loss of axillary and pubic hair.
  • Neurological and ophthalmic involvement: This can result in a loss of visual acuity, extraocular paresis, and bitemporal hemianopsia.
  • Diabetes insipidus: hypernatremia, polyuria, and diluted urine.
• Visual field defects, such as bitemporal hemianopsia, are the most common manifestation of pituitary tumor mass effects