Lecture 17: Anterior Pituitary Disorders Flashcards
What artery supplies the anterior pituitary gland?
Superior hypophyseal artery
What are the 5 types of endocrine cells in the anterior pituitary? What do they secrete?
- Somatotrophs: GH
- Lactotrophs: LH
- Gonadotrophs: LH & FSH
- Corticotroph: ACTH
- Thyrotroph: TSH
How does a GH deficiency present in general?
Growth disorders in children
Abnormal body composition in adults
How does a Gonadotropin deficiency present?
Menstrual disorders and infertility in women.
Decreased sexual function, infertility, and loss of secondary sex characteristics in men.
How does a TSH deficiency present?
Hypothyroidism
How does an ACTH deficiency present?
Hypocortisolism
How does a Prolactin deficiency present?
Failure of lactation
What primarily inhibits prolactin?
Dopamine
How does prolactin inhibit itself?
Release of prolactin can cause a release of dopamine, so it is a negative feedback loop.
When is prolactin secretion highest?
non-REM sleep, usually 4-6am.
When are PRL levels the highest?
Pregnancy
10x increase
Declines rapidly within 2 weeks of parturition.
What keeps PRL levels elevated post pregnancy? How?
Breast-feeding.
The sucking causes a decrease in dopamine.
What hormone is responsible for the stimulation of milk release?
Oxytocin. PRL stimulates ADDITIONAL milk production.
What are the functions of PRL?
- Induce/maintain lactation
- Decrease reproductive function
- Suppress sex drive
How does PRL inhibit reproductive function?
Suppresses hypothalamic release of GnRH and pituitary gonadotropin secretion and impairs gonadal steroidogenesis.
What is the most common pituitary hormone hypersecretion syndrome?
Hyperprolactinemia in both sexes.
What is the MCC of elevated PRL levels > 200?
PRL-secreting pituitary adenomas.
What is the mnemonic for hyperprolactinemia etiologies?
PROLACTINS
* Pregnancy
* Renal failure
* OCPs
* Liver failure
* Adenoma
* Chest wall disease
* Thyroidal disease
* Infiltrative disease
* Nursing/nipple stimulation
* Stalk effect
What are the hallmark signs of hyperprolactinemia in women?
- Amenorrhea
- Galactorrhea (80% of women)
- Infertility
What is the hallmark sign of hyperprolactinemia in men?
Hypogonadotropic hypogonadism
What other significant structure is extremely close to the pituitary gland?
Optic chiasm
When is the ideal time to measure PRL levels?
Fasting morning levels
What kind of tests can we run to exclude other DDx for hyperprolactinemia?
- TSH/FT4 to r/o hypothyroidism
- hCG
- CMP
- Men: serum total and free testosterone, LH, and FSH.
- Women: serum estradiol, LH, and FSH
When is a MRI indicated for evaluating hyperprolactinemia?
If we have a PRL > 200 or unable to find another cause.
Cannot detect microadenomas.