DISORDERS OF THE PITUITARY GLAND: HYPOPITUITARISM

Question 1

What are the hormones of the anterior pituitary gland?

Answer 1

• Growth Hormone
• Thyroid Stimulating Hormone (Thyrotropin) – TSH
• Adrenocorticotropic Hormone (Corticotropin) – ACTH
• Prolactin
• B-Lipotropin
• Gonadotropins:
  Luteinizing Hormone – LH
  Follicle Stimulating Hormone – FSH/ICSH

Question 2

What is Generalized Hypopituitarism? What are the types? What is the onset of symptoms?

Answer 2

Endocrine deficiency syndromes due to partial or complete loss of anterior lobe functions of the pituitary gland

• Primary: Disorders affecting the pituitary gland
• Secondary: Due to disorders of the hypothalamus
• Onset of symptoms of generalized hypopituitarism is usually insidious
  Occasionally, onset is sudden and dramatic

Question 2

How does loss of hormone function occur in hypopituitarism (which organs are lost in which phases)?

Answer 2

Loss of hormone function is usually as follows:
Early:
* GH
* Gonadotropins: LH& FSH

Late:
* ACTH
* TSH
* In panhypopituitarism (global dysfunction of the pituitary gland, leading to a deficiency of all of its hormones), function of all target glands decreases

Question 2

What are the Symptoms and Signs of Generalized Hypopituitarism?

Answer 2

These are easily predicted by the deficiency of the target hormone involved

1. GH: Pituitary infantilism (Peter Pan Dwarfs). This is due to deficiency of GH in children.
   In adults, GH deficiency is usually asymptomatic but the following may be seen:
   - Decreased energy
   - Abnormal body composition and dyslipidemia
2. Gonadotropins: Delayed puberty in children. Others include:
   - Amenorrhea, Decreased libido, infertility
   - Regression of secondary sexual characteristics etc
3. ACTH: Hypoadrenalism
   - Fatigue
   - Hypotension
   - Intolerance to stress and infection
4. TSH: Hypothyroidism
   - Facial puffiness
   - Hoarse voice
   - Bradycardia
   - Cold intolerance
5. In Sheehan’s syndrome, there is pituitary necrosis in the immediate peripartum period.
   * Lactation does not start after childbirth
   * Loss of pubic and axillary hair with fatigue
   * Amenorrhea and secondary infertility
   * Hypotension, coma etc

Question 2

What is the Etiology of hypopituitarism?

Answer 2

• Congenital
• Genetic
• Iatrogenic
  Hypophysectomy, irradiation, Head injury
• Space occupying lesions with compression
  Chromophobe adenoma
  Craniopharyngioma, haemochromatosis
  Other tumors and Secondary metastasis
  Granulomas – sarcoidosis, tuberculosis
• Postpartum hemorrhagic necrosis (Sheehan’s Syndrome)
• Infections: Fungal, parasitic, tuberculosis

Question 2

What are acute symptoms of hypopituitarism?

Answer 2

Acute symptoms are seen:
Severe headache, stiff neck, fever, visual field defects and oculomotor palsies
Somnolence and coma resulting from oedema which compresses the hypothalamus
Vascular collapse resulting from deficient ACTH and cortisol
Bloody CSF

Question 2

Salient features and other symptoms of hormone deficiency?

Answer 2

• Some salient features may include
  Pallor, soft skin
  Paucity of axillary and pubic hair
  Atrophy of the female breast
  Erectile dysfunction in males
• Other symptoms of hormone deficiency:
  Adrenal insufficiency, without change in electrolyte metabolism. Hyperpigmentation of adrenal insufficiency is absent
  Symptoms of hypothyroidism, without myxedema
  Coma from low cortisol with spontaneous hypoglycemia, water intoxication and hypothermia
• Note: Post Pituitary function is usually not defective in hypopituitarism; Posterior pituitary hormones are secreted by the hypothalamus. They are only stored in the post pituitary prior to release

Question 3

What is the Assessment of hypopituitarism?

Answer 3

• Appropriate history
• General Investigations:
• FBC, E&U, Blood sugar profile, Lipid profile
• Measurement of pituitary hormone levels
• Measurement of target organ secretion:
• T3, T4, Cortisol, Testosterone, Progesterone
• Pituitary stimulation tests: TRH, Tetracosactrin (synacthen), Insulin hypoglycemic test, LHRH tests
• Skull radiograph, CT scan, MRI
• Visual field assessment

Question 3

What is the Differential Diagnosis of Hypopituitarism?

Answer 3

1. Anorexia nervosa:
   Female predominance, cachectic, amenorrhea with maintenance of 20 sexual characteristics, GH and cortisol levels are increased
2. Chronic liver disease: including alcohol-related liver disease and hemochromatosis (may cause hypogonadism and general debility)
3. Myotonia dystrophica:
   Progressive weakness; premature balding; cataracts; facial features of accelerated aging
4. Polyglandular autoimmune disease (if the affected glands are target glands of the pituitary)
5. Disorders of other endocrine glands

Question 4

What is the Treatment of hypopituitarism?

Answer 4

• Hormonal replacement, which is normally for life is the appropriate treatment.

NOTE: If both Thyroid hormone replacement is to be given along with cortisol replacement, cortisol replacement is started about a week before thyroid replacement is started

• Treatment of cause, especially when this is known and can be corrected (e.g. surgery for tumors, treatment of infection etc)
• General support may be needed from time to time