how does the hypothalamus regulate the anterior and posterior pituitary gland
- Controls OUTPUT of the ANTERIOR PITUITARY BY MEANS OF RELEASING HORMONES
- Controls OUTPUT of hte POSTERIOR PITUITARY by means of DIRECT NERVE STIMUALTION
What are the two hormones that posterior pituitary secrete
- Antidiuretic hormone (ADH) or Arginine vasopressin (AVP)
- Oxytocin
list the 6 anterior pituitary gland hormones
- prolactin
- growth hormone
- thyroid stimulating hormone
- follicle stimulating hormone
- adrenocorticotropic hormone
- luteinizing hormone
Growth Hormone
Anterior pituitary
- pulsatile secretion with greates levels at ONSET OF SLEEP (at night)
deficiency of Growth hormone
- Childhood = dwarfism
–> short stature, micropenis, increased fat, high-pitched voice
TX = replacement therapy with recombinant GH
Growth hormone Hypersecretion
- Youth –> Gigantism
- Adults –> Acromegaly
–> increased height, hand and foot sizes
–> soft tissue swelling
–> generalized visceromegaly (heart and tongue)
TX
–> surgery for tx of tumors
–> Somatostatin analogues
–> dopamine agonists
–> GH antagonist = Pegvisomant
Prolactin
anterior pituitary
- Pulsatile secretion with peaks during REM SLEEP
- Under hypothalamic inhibition by Dopamine
Hyperprolactinemia
- Most common benign neoplasm (prolactomas)
- Female = amenorrhea, galactorrhea, infertility, mild hisutism
- Male = diminished libido or visual loss from optic nere compression, headaches, gynecomastia, impotence
- TREATMENT
–> dopamine agonist = alleviate gonadal dysfunction
–> surgery = debulking
–> readiotherapy
ADrenocorticotropin hormone (ACTH)
Anterior pituitary
- pulsatile secretion with a circadian rhythm (peaks at 6am and lowest at midnight)
- Stimulates the adrenal gland to produce corticosteroids and androgens
ACTH defiiciency
Primary adrenal insufficiency or ADDISON’S DISEASE
- results in secondary adreanl insufficeincy with increasing fatigue, weakness, anorexia, nausea, vomiting, weight loss, low blood pressure, depression, sometimes hypoglycemia
- TREATMENT = LUCOCORTICOID; hydrocortisone or prednisone
ACTH hypersecretion
- CUSHING SYNDROME
- most are iatrogenic
- thin, brittle skin, central obesity with moon facies, buffalo hump, hypertension, purple striae and easy brusiing
- TREATMENT
- surgery followed by cortisol replacement
- pituitary radiation if surgery unsuccessful
- adrenalectomy if necessary
FSH and LH
anterior pituitary
- regulated by GnRH
- secreted in discrete pulses every 60-120 minutes
FSH and LH deficiency
- WOmen = menstrual irregularities, infertility, decreased vaginal secretions, decreased libido, and breast atrophy, osteoporosis
–> TX = cyclical replacment of estrogen and progesterone, gonadotropin therapy for ovulation induction, hCG to induce ovulation
- MALES = decreased libido and potency, decreased muscle mass with weakness, reduced beard and body hair growth, soft testes and osteoporosis
–> TX = testosterone replacement and hCG restores fertility
FSH and LH hypersecretion
- Gonadotropin producing adenomas typically produce only SMALL AMOUNTS OF FSH AND LH
- may see attenutaed Lh and hypogonadism due to compression of pituitary stalk with optic chaism pressure causing visual problems
- TREATMENT = if large, surgery followed by radiation if postoperative rediual mass is present
Thyroid stimulating hormone (TSH) deficiency
- fatigue; dry skin, cold, hair loss; wiehgt gain with poor appetitie; puffy face hands and feet (myxedema)
- TREATMENT = levothyroxine
TSH hypersecretion
- Heat intolerance, palpitations, weight loss with increased appetitie, goiter, periorbital edema and proptosis (exophthalmia)
- TREATMENT = surgery followed by somatostatin analogue
**GRAVES DISEASE**
AVP – VASOPRESSIN
posterior pituitary
- reduces water excretion by increasing concentration of urine
- secretion regulated by the effective osmotic pressure of body fluids –> osmoreceptors
Vasopressin deficiency
DIABETES INSIPIDUS
- abnormally large volumes of dilute urine
- idiopathic or vascular and many other caues
- urinary frequency, enuresis and or nocturia, thirst and polydipsia
- TREATMENT = synthetic analog of AVP = DESMOPRESSIN
vasopressin HYPERsecretion
SIADH = syndrome of inappropriate ADH
- decreased volumes of more highly conc urine
- hyponatremia and water retention
- IF ACUTE, water intoxication; headache, confusion, anorexia, nausea, vomiting, coma, convulsions and death
- TREATMENT
–> ACUTE = restrict total fluid intake
–> chornic demeclocycline or fludrocortisone
Pituitary apoplexy
- due to intrapituitary hemorrhagic vascular event
- endocrine emergency
- ACUTE SYMPTOMS = severe headache, bialteral visual changes, in severe cases, CV collapse, loss of consciousness
- May result in severe hypoglycemia, hypotension, CNS hemorrhage and death
- TREATMENT = surgery
