Anterior Pituitary Flashcards
Which artery supplies the anterior pituitary to carry hormones from the hypothalamus to the anterior pituitary
Superior hypophyseal artery
What artery supplies the posterior pituitary gland after hypothalamic hormones travel through direct neural extension?
Inferior hypophyseal artery
Which hormone released from the hypothalamus increases prolactin release from the anterior pituitary gland? Which hormones inhibit prolactin release from the anterior pituitary gland?
Prolactin-releasing peptide
Prolactin-inhibiting factor (may be dopamine)
Which hormone is released from the hypothalamus to stimulate the anterior pituitary gland to release growth hormone?
Growth hormone releasing hormone
What are the 5 types of endocrine cells in the anterior pituitary that are defined by the hormones they secrete?
Somatotrophs: GH
Lactotrophs: LH
Gonadotrophs: LH and FSH
Corticotroph: ACTH
Thyrotroph: TSH
Underproduction of hormones released by the pituitary gland to cause symptoms based on which hormones are under secreted
Hypopituitarism
What are inherited disorders that cause hypopituitarism?
Pituitary dysplasia/aplasia
Congenital CNS mass
Congenital hypothalamic disorders
What are traumatic conditions that can cause hypopituitarism?
Surgical resection, radiation, head injury
What are tumors that can cause hypopituitarism?
Pituitary adenoma, pituitary metastasis
What are inflammatory causes of hypopituitarism?
Hemochromatosis, sarcoidosis
What are vascular causes of hypopituitarism?
Arteritis, sickle cells disease
What are infection causes of hypopituitarism?
Fungal, parasite, TB
What are congenital causes of hypopituitarism?
Prader Willi syndrome
Kallmann syndrome
What are acquired conditions that cause hypopituitarism?
Radiation, TBI, chemotherapy, ischemic stroke
What are functional causes of hypopituitarism?
Opioid use, normal aging, malnutrition, CKD
Loss of this pituitary hormone will cause growth disorders in children and abnormal body composition in adults
GH deficiency
Loss of this pituitary hormone will cause menstrual disorders and infertility in women and decreased sexual function, infertility, and loss of secondary sex characteristics in men
Gonadotropin deficiency
Loss of this pituitary hormone will cause hypothyroidism in children and adults
TSH deficiency
Loss of this pituitary hormone will cause hypocortisolism
ACTH deficiency
Loss of this hormone will cause failure of lactation
Prolactin deficiency
Name the correct anterior pituitary hormone that is triggered by the following hypothalamic releasing hormones:
1) CRH
2) TRH
3) GnRH
4) GHRH
5) Dopamine (inhibits)
1) ACTH
2) TSH
3) LH and FSH
4) GH
5) Prolactin
Prolactin is synthesized in ____. What condition causes significant Lactotrope cell hyperplasia?
Lactotrophs; pregnancy and first few months of lactation
What are normal serum PRL levels in women and men in absence of pregnancy?
Women: 10-25 ug/L; men: 10-20 ug/L
How is prolactin kept from being active without pregnancy?
In an inhibited state most of the time and inhibited by dopamine type 2 receptors. PRL increases dopamine to inhibit itself
What are conditions where serum PRL levels would rise mildly and transiently?
-Exercise, meals, sexual intercourse
-Breast exam, chest wall injury
-Minor surgical procedures, general anesthesia
-Stress of any kind
Pulsatile with highest secretion during non-REM sleep with peak between 4-6 AM (circulating half life of 50 mins)
How does PRL change during pregnancy?
-Increase tenfold during pregnancy in response to elevated estrogen and progesterone
-decline rapidly within 2 weeks of parturition if breast-feeding not initiated
How does breast feeding impact prolactin?
Suckling stimulates reflex increases in PRL levels that last about 30-45 min due to decrease in dopamine released by hypothalamus
Suckling also stimulates the posterior pituitary to release oxytocin
Oxytocin stimulates milk release and prolactin stimulates milk production
Magnitude of PRL increase is proportional to degree of preexisting lactotroph hyperplasia due to estrogen
What are the functions of prolactin?
Induce and maintain lactation, decrease reproductive function, and suppress sex drive
Inhibits reproductive function by suppressing hypothalamic GnRH and pituitary gonadotropin secretion and impairing gonadal steroidogenesis in women and men
—>@ovary leads to hypoestrogenism and anovulation
—>shortened or inadequate literal phase of menstrual cycle
—>in men, low testosterone levels and decreased spermatogenesis—> decreased libido and fertility
What is the etiology of hyperprolactinemia?
Most common pituitary hormone hypersecretion syndrome in men and women
PRL-secreting adenomas are most common cause of PRL >200 ug/L (more common in women, may be familial MEN type 1 or 4)
Microprolactinoma (less pronounced elevation) due to drugs (lots of psych drugs), pituitary stalk compression, hypothyroidism, or renal failure
Pregnancy
Renal failure
Oral contraceptives
Liver failure
Adenoma
Chest wall disease
Thyroidal disease (hypothyroidism)
Infiltration disease of the pituitary
Nursing/nipple stimulation
Stalk effect
How does hyperprolactinemia present in women?
Amenorrhea, galactorrhea, and infertility
May also complain of decreased libido, weight gain, mild hirsutism
-vaginal dryness/atrophy, irritability, anxiety and depression (estrogen deficiency)
-long term: osteopenia, reduced muscle mass
How does hyperprolactinemia present in men?
Hypogonadotropic hypogonadism
-decreased libido
-impotence/erectile dysfunction
-infertility
-gynecomastia
-galactorrhea (less often than women)
If long-standing, osteopenia, reduced muscle mass, decreased facial hair growth
What should you ask about when evaluating hyperprolactinemia causes?
Pregnancy? Medications? Renal failure? Thyroid disease? Headache or vision changes? (Rule out tumor @ optic chiasm)
What physical examinations should you do for hyperprolactinemia?
Test for chiasmal syndrome, signs of hypothyroidism, or hypogonadism
What lab tests can be ordered for hyperprolactinemia?
Serum prolactin concentration: basal, fasting morning PRL (may increase during sleep, strenuous exercise, occasionally emotional or physical stress, breast stimulation, high-protein meals)—> high value should be repeated and confirmed
TSH/T4: to exclude hypothyroidism
serum HCG: in every woman
CMP: to rule out kidney disease
Serum total and free testosterone, LH, FSH: evaluate for hypogonadism in men
Serum estradiol, LH, FSH in women who have amenorrhea for hypogonadism
If no other cause is determined and PRL elevated or if PRL >200, what can be done to assess for hyperprolactinemia cause? What are concerning findings?
MRI: sella turcica lesion- secretion of other pituitary hormones should be evaluated
If normal, idiopathic hyperprolactinemia diagnosis
Can be due to micro adenomas not seen on imaging
How is hyperprolactinemia treated?
Specific management of cause
Normalize PRL levels with estrogen, estrogen/progesterone, or testosterone replacement if microprolactinomas (<1 cm)
Dopamine agonists regardless of underlying cause
What are the dopamine agonists and their MOA?
Cabergoline and bromocriptine: suppress PRL secretion and synthesis and lactotrope cell proliferation
This is a long-acting dopamine agonist and suppresses PRL for >14 days after one oral dose with less adverse effects and drug intolerance
Cabergoline