Pituitary Hyperfunction Flashcards
The vast majority of Pituitary Tumors secrete what hormone(s)
Prolactin (50%)
Non-Secretory (40%)
Functions of Prolactin
Milk PRODUCTION (not let-down) Oppose action of Gonadotropins (FSH & LH) and estrogen Inhibits GnRH release
How might a Prolactinoma result in low testosterone in males?
Prolactin opposes the action of Gonadotrophins and inhibits GnRH release
MOA for Hyperprolactinemia
Deficiency of Dopamine
Defective delivery of Dopamine
Insensitivity to Dopamine
Stimulation of Lactotroph cells (by oestrogen)
What are some pathologies/diseases that can cause Hyperprolactinemia
Prolactinoma Acromegaly Pituitary stalk disease (or compression) Renal insufficiency (dec. prolactin clearance) Seizures Cirrhosis etc.
Medications that can cause Hyperprolactinemia
Antihypertensives (Verapamil, Methydopa) GI meds (Metoclopramide, Domperidone, H2 blockers) Psych drugs (SSRIs, MAO inhibitors, Chlorpromazine, Atypicals)
Signs/Symptoms of Hyperprolactinemia
Female:
- galactorrhea
- Menstrual irregularity
- Infertility
- loss of pubic hair
Male:
- galactorrhea
- Impotence (erectile dysfunction & dec. libido)
- Visual Field Abnormalities
- Extraocular Muscle Weakness
- loss of pubic hair
The earliest change that occurs with Hyperprolactinemia (in females) is the loss of ____ and ___ due to the inhibition of _____ release from the Hypothalamus
LH and FSH; GnRH
*remember that prolactin opposes the actions of gonadotrophins and inhibits GnRH
Treatment for Hyperprolactinemia
Dopamine agonist therapy (1st line)
Monitor w/o tx if asymptomatic with stable prolactin and no loss of sex hormones
*surgery and radiotherapy have limited use
Examples of Dopamine Agonists (for Hyperprolactinemia treatment) (2 total)
Bromocriptine
Cabergoline
Side Effects of Dopamine Agonist
Orthostatic Hypotension
Psychosis
Nausea & Vomiting
Sleep Disturbances
Acromegaly is due to _______ excess in adults
Growth Hormone
Signs of Acromegaly (GH excess)
Bone growth (acral changes like shoe size, ring size, hat size) neuromuscular Thickening of skin (heel pad) Hypertension Resp. problems Cardiomyopathy
IGF-I
insulin-like growth factor I (good for GH monitoring)
Diagnostic methods for Acromegaly
- Measure IGF-I (stable and unaffected by meal; more reliable than GH)
- Failure to suppress GH < 1 ng/mL after oral glucose administration
Which sign/symptom of Acromegaly (GH excess) has the most impact on mortality
Acromegaly + Cardiac disease (HTN, cardiomyopathy, etc.)
- life expectancy dropped by 10 YEARS!!
Treatments for Acromegaly
Medication (1st line)
- Dopamine Agonists (direct inhibition of GH)
- Somatostatin Analogs (direct inhibition of GH)
- GH receptor antagonists (most potent)
Surgery
Radiotherapy
Example of GH Receptor Antagonist
Pegvisomant
The earliest presenting symptom in women with hyperprolactinemia is
infertility
* due to loss of mid-cycle surge of LH and FSH
What symptoms always appears along with amenorrhea?
galactorrhea
(T/F) Dopamine agonists reduce pituitary tumor size.
True
_______ (organs) are stimulated by GH to synthesize _______ , which stimulate other target tissues
- bone, muscle, fat, and liver
2. IGF-1
Pattern of GH secretion
pulsatile
Examples of Somatostatin analogs (for acromegaly treatment)
Octreotide
Lanreotide
- -otides
