1. Pituitary dysfunction

2. Basics
Located in sella turcica, a bony cavity in
sphenoid bone, at the base of the brain
Functionally controlled by & connected to
hypothalamus by infundibulum

3. Hormones
 2 lobes- anterior & posterior
 Anterior lobe- synthesizes & secretes
 ACTH- controls adrenals
 TSH- controls thyroid
 Growth hormone- controls growth
 Prolactin- controls breast milk production
 LH & FSH- gonadotrophins- regulate gonads
 Posterior lobe- stores & releases
 Oxytocin- released from paraventricular nucleus of
hypothalamus, regulates uterine contractions during delivery
 ADH/AVP- released from supraoptic nucleus of hypothalamus,
regulates water & osmolality

4. Control of pituitary function
 Hypothalamus- destruction/interruption
 Reduced GH, LH, FSH, TSH, ACTH, AVP, oxytocin
 Increased prolactin- dopamine acts as prolactin inhibitory factor
 Feedback from target glands-
 Thyroid
 Adrenal cortex
 Gonads
 Pituitary damage/removal results in-
 2° hypogonadism/hypothyroidism/hypoadrenalism
 Decreased function of GH & prolactin

5. Pituitary dysfunction
 Overproduction-
 Adenoma- any hormone
 Acromegaly- GH
 SIADH- AVP- euvolemic hypotonic hyponatremia
 Underproduction-
 Hypopituitarism- many hormones
 Sheehan syndrome- many hormones
 Short stature, in children- GH
 Diabetes insipidus- AVP- polyuria, polydipsia, ± hypernatremia

6. Pituitary adenoma
 ~10% of intracranial tumors
 Secretory or non-secretory
 Occassionally part of MEN-1 syndrome
 Micro- prolactin-F, ACTH or Macro- GH, prolactin-M
 Causes-
 Hormone excess- prolactin, GH, ACTH, TSH, LH/FSH
 Surrounding invasion– bitemporal hemianopsia; headache;
III, IV, V, VI cranial nerve defect; complex
partial seizure
 Evaluation-
 Lateral skull X-ray, MRI
 Evaluate hormonal defect(s)

7. Treatment
Bromocriptine
Trans-sphenoidal surgery
Radiotherapy

8. Hyperprolactinemia
 Due to excess production from prolactinoma
or disinhibition b’cos of pituitary stalk
compression or reduced dopamine
 Raised prolactin inhibits GnRH,
thus inhibiting gonadal steroids
 Causes-
 Physiologic- pregnancy, breastfeeding
 Drugs- antipsychotics, antiemetics, α-methyldopa, estrogens
 Diseases- pituitary adenoma, CRI, hypothyroidism, sarcoidosis
 Post-epileptic seizure prolactin level increases

9. Clinical
 Symptoms-
 Female- irregular menstruation
 Males- decreased libido, erectile dysfunction
 Both- infertility, galactorrhea, headache
 Dx-
 Serum prolactin levels
 X-ray skull, MRI brain
 Rx-
 Dopamine agonists- cabergoline, bromocriptine
 Trans-sphenoidal surgery, if required

10. GH excess
 Due to pituitary macroadenoma
 Causes gigantism, if before epiphyseal fusion
or acromegaly, in adults
 Manifestation-
 Large hands, coarse facial features, malocclusion
 Weight gain, HT, cardiomegaly, IGT/DM
 Degenerative arthritis
 Dx- IGF-1, GH after glucose load, MRI
 Rx- trans-sphenoidal resection

11. Hypopituitarism
 Deficiency of one or more hormones
 Common- GH or gonadotrophin deficiency
 Causes-
 Pituitary adenoma, apoplexy, surgery, RT, trauma
 Hypothalamic tumors- craniopharyngioma
 Granulomatous or infiltrative diseases
 Sheehan syndrome- postpartum pituitary infarction
 Kallmann syndrome- LH/FSH deficiency with anosmia
 Dx- MRI, confirm hormone deficiencies
 Rx- hormone replacement