Hyposecretory states Flashcards
What are the two nuclei in the hypothalamus that send axons down into the posterior pituitary?
Paraventricular
Supraoptic
What are the six hormones that are secreted by the anterior pituitary?
ACTH TSH PRL LH FSH GH
What are the two hormones released by the posterior pituitary?
ADH
Oxytocin
What is the inhibitory and promoting signals for Prolactin release?
Dopamine = inhibiting TSH = promoting
What does GH do in the liver? What does this do?
causes IGF production, which acts on target tissues
What is hypopituitarism?
Decreased secretion of anterior and/or posterior pituitary hormones resulting from pituitary, hypothalamus, or parasellar disease
What is the most common cause of hypopituitarism?
80% primary pituitary disease
What percent of hypopituitarism is caused by hypothalamic disease?
13%
What is the sinus that sits anterior to the pituitary?
Sphenoid sinus
What are the four major primary causes of hypopituitarism?
- Tumors
- Surgery
- Radiation
- Infarction
What type of growth can cause hypopituitarism?
Adenomas
How long does it take for hypopituitarism to present following head/neck radiation?
Months to years
What is Sheehan syndrome? SSX?
hypopituitarism after postpartum hemorrhage d/t infarct of the pituitary
Amenorrhea and inability to lactate following prego
What is pituitary apoplexy? Ssx?
Hemorrhage into a pituitary adenoma
Sudden onset of a headache, and diplopia from pressure on oculomotor nerves
What are the infiltrative diseases that can cause hypopituitarism?
- Sarcoidosis
- Hemochromatosis
- Lymphocytic hypophysitis
What is lymphocytic hypophysitis?
Lymphocytes invade and cause destruction of pituitary cells
What is the genetic mutation that can cause hypopituitarism ?
Pit-1
prop-1
What is the difference between primary and secondary empty sella syndrome?
Primary = defect in the diaphragm sella, allowing CSF pressure to enlarge the sella
Secondary = space resulting from a pituitary adenoma that has been removed by surgery or radiation
What are the ssx of cortisol deficiency?
- Weakness/fatigue
- Anorexia
- Vague abdominal pain
- Weight loss
- hypoglycemia
How do you determine ACTH deficiency?
Low cortisol with simultaneous low ACTH
Does primary or secondary adrenal insufficiency cause hyperpigmentation? Why?
Primary, since increased POMC production causes increased MSH (by product of its breakdown) to cause hyperpigmentation
Does primary or secondary adrenal insufficiency cause aldosterone deficiency? Why? What metabolic disturbance does this cause?
Primary, since Renin-angiotensin not regulated by ACTH
Hyperkalemia
How do you diagnose adrenal insufficiency?
Morning cortisol less than 3 or greater than 18
What is the cortrosyn stimulation test? What indicates a normal test?
- Obtain a baseline cortisol level
- Administer 250 mcg of ACTH
- Check serum at 30 and 60 minutes after injection
- If rises more than 18, abnormal
What is Metyrapone? Use?
Medication that blocks conversion of 11-deoxycortisol to cortisol.
This should increase ACTH in normal patients
How is insulin used to diagnose ACTH deficiency?
Giving insulin will cause hypoglycemia, and should increased ACTH
What is the treatment for ACTH deficiency?
Give 15-30 mg of hydrocortisone daily
2/3 dose at rising, 1/3 dose afternoon
When should patients with secondary ACTH deficiency administer a higher dose?
Under periods of illness
How do you assess the adequacy of treatment for ACTH deficiency?
Check BP, lytes, and general wellbeing
Do patients with secondary adrenal insufficiency (decreased ACTH production) need supplementary aldosterone? Why or why not?
No, because only primary adrenal insufficiency causes a loss of aldosterone
What are the findings of TSH deficiency?
Low T4 and low TSH
What is the treatment for TSH deficiency? Goal?
L-thyroxine, with the goal being normal T4 serum values
Why do you want to fix hypocortisolism prior to fixing low TSH?
Will cause an adrenal crisis if fix TSH first d/t increased clearance of cortisol
True or false: TSH measurements in secondary hypothyroidism are useless as a guide to adequacy of L-thyroxine dosing
True
What are the ssx of hypogonadotropin?
anovulation, infertility
What are the lab findings of gonadotropin deficiency in women?
- Low estradiol
- Low LH
- Low FSH
What is the progesterone challenge for female gonadotropin deficiency?
Failure to bleed
What is the treatment for male hypogonadotropism? (if seeking fertility vs not)
Testosterone if not seeking
LH/FSH if pituitary disease
GnRH if hypothalamic disease
What is the treatment for female hypogonadotropism? (if seeking fertility vs not)
Estrogen/progestin replacement
FSH/LH if pituitary disease
Pulsatile gonadotropin GnRH in hypothalamic disease
What are the ssx of GH deficiency in children?
Short stature /growth failure
What are the ssx of GH deficiency in adults?
- Diminished muscle mass
- Increased fat mass
- Increased LDL
- Decreased bone mass
Why are random GH levels not helpful?
No standarized ranges, and peaks at night
What is the hormone that is most commonly measured for GH deficiency? How can you determine if there is disease present?
IFG-1
Age and gender ranges
How is insulin used to diagnose GH deficiency?
Give insulin, measure GH. Normal response should be an increased in more than 10 ng/ml
How is arginine + GH releasing hormone used to diagnose GH deficiency?
Given, then measure at 0, 30, 60 etc
True or false: when 3-4 pituitary deficiencies exist, one can assume GH deficiency exists as well
True
What is the order of the likelihood of hypopituitarism (most to least likely)?
GH
LH/FSH
TSH
ACTH
What is the treatment for GH deficiency? How do you monitor this?
Recombinant GH preps
Monitor with IGF-1 levels
What is the primary sign of prolactin deficiency?
Inability to lactate
How do you diagnose and treat prolactin deficiency?
Typically not done since hard to distinguish low from normal levels
No treatment
What are the two stimuli for ADH release?
- Increased plasma osmolality
2. Decreased plasma volume
What is the MOA of ADH? (what does binding to each of its receptors do)?
- Binds to V1 receptors on the kidneys to vasoconstrict
- Binds to V2 on renal tubules to insert aquaporins
What is central diabetes insipidus?
Deficiency in vasopressin d/t damage of hypothalamus-posterior pituitary region
What are the common causes of central diabetes insipidus?
- Head trauma
- Neurosurgery
- Tumors/aneurysms
- Infiltrative disease
What is the primary sign of central diabetes insipidus?
Hypotonic polyuria
What are the electrolyte disturbances in diabetes insipidus?
Hypernatremia
What is the MRI change with diabetes insipidus?
Loss of bright spot on MRI for the potuitary
What is the treatment for central diabetes insipidus?
- ins=outs
- Desmopressin
When is desmopressin indicated for central diabetes insipidus?
If urine volumes is greater than 4 L per day
What is desmopressin?
Synthetics vasopressin analogue that binds to V2 receptors on the kidney
How long does desmopressin take to work?
30-60 minutes
What is transient ADH deficiency? When is it seen?
Swelling on the posterior pituitary causes a lack of ADH
Commonly seen after pituitary surgery/removal of pituitary tumor
What is the most common secretory pituitary tumor?
Prolactinoma
High prolactin decreases the secretion of what other hormones?
GH and FSH
Prolactin level less than 100, but elevated, is most indicative of what pituitary pathology?
Stalk compression, NOT a prolactinoma
True or false: with prolactinomas, there is a direct correlation between size of a tumor, and prolactin levels
True
Why does stalk compression cause an increase in prolactin?
Interruption of the dopamine inhibition
If T4 is very low, but TSH is only mildly elevated, then what should you suspect?
Pituitary disease
True or false: women with primary hypothyroidism tend to have heavy menstrual flows.
True
What are the prolacin levels that may indicate a prolactinoma less than 1 cm in size? 1-2 cm in size? More than 2 cm in size?
- Less than 1, less than 200 ng/ml
- 1-2 cm, 200-1000 ng/ml
- More than 2 cm, more than 1000 ng/mL
What is Addison’s disease? What are ACTH levels with this?
Primary adrenal insufficiency where the adrenal glands fail to make cortisol. ACTH are elevated with this
What happens to estrogen, LH, and FSH levels with menopause? How is this different than hypogonadotropism?
Lower estrogen, but increased FSH and LH
all low in hypogonadotropism
What is the progesterone challenge?
Give a woman progesterone, then take it away suddenly should cause menstruation. If it does not, then there is not a high enough estrogen level
What do low LH and FSH cause in men (respectively)?
Low LH = lower testosterone
Low FSH = low sperm count
What is the classic facial finding with GH deficiency?
Fine facial wrinkling
Where are osmoreceptors located? Baroreceptors?
Osmoreceptors = CNS Baroreceptors = atrium of the heart and vaculature
What is the difference between micro and macroadenomas?
Micro = less than 1 cm Macro = more than
Only a slight elevation in TSH when the free T4 is very low suggests what?
Pituitary disease
Women with primary hypothyroidism tend to have what type of menstrual flows?
Heavy
What is the way to stimulate GH?
Arginine + GhRH