EXAM #1: HYPOPITUITARISM Flashcards
What inhibits prolactin secretion from the anterior pituitary?
Dopamine, which TONICALLY inhibits prolactin release
*Thus, anything that disrupts dopamine can cause prolactin INCREASE
What is hypopituitarism?
Decreased secretion of anterior and/or posterior pituitary hormones
What is the definition of panhypopituitarism?
Decreased secretion of all pituitary hormones
Describe the basic etiology of hypopituitarism.
There are three basic causes of hypopituitarism:
1) Pituitary disease (most common)
2) Hypothalamic disease
3) Idiopathic causes
What can cause the insidious onset of panhypopituitarism?
Radiation exposure leading to panhypopituitarism months-years s/p
What is pituitary apoplexy? What are the symptoms of this condition?
- Patient with pituitary tumor
- Tumor hemorrhages suddenly
*Sx include sudden onset excruciating headache and diplopia
In terms of clinically describing hypopituitarism, what does secondary mean?
Problem is in the pituitary gland or hypothalamus, NOT the target gland itself (primary)
*E.g. when referring to the thyroid; defect in TRH or TSH is secondary hypothyroidism vs. T4 which would be primary
What is the physiologic consequence of ACTH deficiency (hormone)?
Cortisol deficiency
What are the signs and symptoms of ACTH deficiency?
Sx=
- Weakness/fatigue
- Anorexia
- Abdominal pain
- Weight loss
Signs=
- Postural hypotension/ reflex tachycardia
- Vascular collapse
- Pallor
- Hypoglycemia
What labs clue you into secondary ACTH deficiency?
Simultaneously low ACTH and cortisol
What is missing from secondary ACTH deficiency vs. primary?
1) Hyperpigmentation
2) Aldosterone deficiency
*I.e. no salt wasting, no hyperkalemia
How is adrenal insufficiency diagnosed?
1) Morning cortisol
2) Cortrosyn stimulation test
3) Measure ACTH
Cortisol, 18= normal
What tests can be used to provoke a high ACTH level?
1) Metyrapone
2) Insulin induced hypoglycemia
*If these are positive; secondary
How is adrenal insufficiency treated?
Hydrocortisone (15-30mg daily)
Note that the patient will need higher doses during times of stress/illness (This is called “stress-dosing”)
How is secondary hypothyroid diagnosed?
1) Low T4 (primary)
2) Low TSH (should be high–secondary)
How is hypothyroid treated?
L-thyroxine
*Goal is to maintain normal T4 and a sense of well-being NOT TSH measurements
If a patient has hypothyroid, what do you need to check first before starting treatment?
Adrenal function
What are the symptoms of gonadotropin deficiency?
1) Infertility
2) Irregular periods (female)
3) Osteopenia/perosis
How is secondary gonadotropin deficiency diagnosed?
Low:
1) Estradiol or testosterone
2) Low LH/FSH
How is gonadotropin deficiency treated in men?
1) Testosterone replacement if NOT seeking fertility
2) IF seeking fertility
- LH/FSH for pituitary disease
- GnRH for hypothalamic
How is gonadotropin deficiency treated in women?
1) Estrogen-progestin replacement
2) IF seeking fertility
- LH/FSH for pituitary disease
- GnRH for hypothalamic
What is the mainstay of GH deficiency diagnosis?
IGF-1 levels
What is the likelihood of deficiencies in panhypopotuitarism?
1) GH
2) LH/FSH
3) TSH
4) ACTH
How is GH deficiency treated?
Recombinant GH
*Goal of therapy is to maintain IGF-1 level and sense of well-being
What is the treatment for prolactin deficiency?
None–no treatment available
What are the to stimuli that induce vasopressin release?
1) Increases in plasma osmolality
2) Decreased plasma volume
Where are V1 receptors located?
Vasculature
Where are V2 receptors located?
Renal tubules
What happens when vasopressin binds V2 receptors?
1) Synthesis of aquaporins
2) Aquaporins are inserted into collecting duct membrane
Thus, there is reabsorption of solute free water
What is central diabetes insipidus (DI)?
Deficiency of vasopressin due to posterior pituitary problem
How is central DI diagnosed?
1) Hypotonic polyuria
2) Hypernatremia
3) Loss of pituitary bright spot on MRI
How is central DI treated?
Mild= ingest enough water to keep-up
Severe= Desmopressin (ddAVP) synthetic vasopressin analogue
What will high prolactin cause?
Low FSH/LH i.e. low estrogen/testosterone?
What is a prolactin level less than 100 most associated with?
Pituitary stalk compresion
