Pituitary, Thyroid, Adrenal Flashcards
Most common cause of hyperthyroidism
Grave’s Disease
Describe the mechanism of Grave’s Disease
Autoimmune → circulating Thyroid Stimulating Immunoglobulins (TSI) → binds to TSH receptor on thyroid → makes lots of thyroid hormone
T/F: Grave’s Disease presents as diffuse asymmetric goiter.
False: symmetric
Exophthalmus and infiltrative dermopathy are specific to which disease?
Grave’s Disease
Name the diseases (2)
• Focal and/or diffuse hyperplasia of thyroid follicular cells
• Activating somatic mutations of genes for TSH receptor
Toxic Adenoma
Toxic Multinodular Goiter
Name the disease:
Inflammation/destruction of thyroid gland
Thyroiditis
High fT4, low TSH suggests:
Thyroid origin of hyperthyroidism
High fT4, high TSH suggests:
Pituitary origin of hyperthyroidism
(Central hyperthyroidism)
High TSH due to oversecretion by tumor
If central hyperthyroidism, next diagnostic step is:
Pituitary MRI to find tumor
If thyroiditis, next diagnostic step is:
Check ESR
If Grave’s disease, next diagnostic step is:
Check TSI antibodies
The best test for diagnosis of type of hyperthyroidism is:
Radioactive thyroid imaging
Inflamed thyroid (thyroiditis), damaged membrane show ____ radioiodine uptake.
None/ ~0-2%
Over-functioning thyroid show ____ radioiodine uptake.
> 25%
Treatment for thyroiditis
Beta blocker ONLY
Drug of choice for treating pregnancy and lactation patients with hyperthyroidism
Propylthiouracil (PTU)
Name 2 drugs that inhibit synthesis of thyroid hormone
Methimazole
Propylthiouracil (PTU)
T/F: Surgery is one of the recommendations for treating hyperthyroidism
False. Not recommended since it can be treated non surgically
Treatment regimen for pregnant patient with hyperthyroidism
PTU for 1st trimester → then methimazole
Methimazole has teratogenic effect
Primary adrenal insufficiency is caused by:
Deficiency in:
Destruction of adrenal cortex
glucocorticoid
minderalocorticoid
adrenal androgen
All of the following are causes of Primary adrenal insufficiency EXCEPT: A. Polyglandular failure syndromes B. Tuberculosis/histoplasmosis C. Sarcoma D. Hemorrhage
C. Lung/breast carcinoma
Secondary adrenal insufficiency is caused by:
Deficient ACTH release from pituitary
or
Deficient hypothalamic release of CRH
Describe the expected levels in primary adrenal insufficiency:
Cortisol:
Aldosterone:
ACTH:
Cortisol: low
Aldosterone: low
ACTH: high
Describe the expected levels in secondary adrenal insufficiency:
Cortisol:
Aldosterone:
ACTH:
Cortisol: low
Aldosterone: normal
ACTH: low
Primary OR secondary adrenal insufficiency:
Hyperkalemia
Primary
Primary OR secondary adrenal insufficiency:
Fluid depletion
Primary
Primary OR secondary adrenal insufficiency:
Hyperpigmentation
Primary
Failure to suppress low dose (1 mg) overnight dexamethasone suppression test suggests:
Cushing’s (ACTH-dependent)
Increased ACTH suggests (2)
Pituitary tumor
Ectopic
Decreased ACTH suggests (2)
Adrenal tumor
Exogenous
> 50% suppression in high dose DST suggests
Pituitary Cushing’s
No suppression in high dose DST suggests
ectopic Cushing’s
T/F: Primary hypothyroidism is less common than secondary hypothyroidism.
False. 95% are primary.
All of the following are causes of primary hypothyroidism EXCEPT: A. Autoimmune B. Destructive C. Hypothalamic disorder D. Drug induced E. Hereditary
C. This is secondary hypothyroidism cause. Also pituitary disorder.
All of the following are symptoms of hypothyroidism EXCEPT: A. Cold intolerance B. Weight loss C. Dry skin D. Edema
B. Weight gain
Most common form of hypothyroidism
Hashimoto’s Thyroidism
Thyroid peroxidase antibodies (TPO) are found in what disease?
Hashimoto’s
Low fT4, high TSH suggests
Primary hypothyroidism: thyroid origin
Low fT4, low TSH suggests
Secondary hypothyroidism
Preferred therapy for hypothyroidism
Levothyroxine (T4)
Goal of therapy for primary hypothyroidism
Achieve normal TSH
Goal of therapy for secondary hypothyroidism
Achieve normal fT4
TSH will always be low
T/F: Most thyroid nodules are malignant.
False. 95% are benign adnenomas or cysts
Only 5% are malignant
Which of the following is NOT a cause of prolactin elevation? A. Pregnancy B. Secondary hypothyroidism C. Antipsychotics, metoclopramide D. Renal failure
B. Primary hypothyroidism: elevated TRH stimulates lactotrophs –> pituitary enlargement
Also: prolactin secreting pituitary tumor
Name the 2 dopamine agonists used to treat elevated prolactin
Bromocriptine
Cabegoline
T/F: Nausea is a worse in Bromocriptine than Cabegoline
True
Minimize effect by increasing dose slowly
T/F: The most effective treatment for elevated prolactin is surgery to remove the prolactinoma.
False. DA agonist therapy is VERY effective.
• Surgery NOT uniformly effective
o High rate of recurrence
o Risk of damaging healthy pituitary
• Prolactinomas are the only pituitary tumors treated medically
GnRH is secreted from ____ and stimulates ____ to secrete ___.
hypothalamus
anterior pituitary
LH, FSH
Expected lab values in primary hypogonadism
Testosterone:
LH/FSH:
Testosterone: low
LH/FSH: high
Expected lab values in secondary hypogonadism
Testosterone:
LH/FSH:
Testosterone: low
LH/FSH: low or low-normal
T/F: 90% of pituitary masses are cystic lesions.
False. Pituitary adenoma
What test assess for acromegaly?
IGF-1 produced in liver
GHRH (hypothalamus) –> GH (pituitary) –> IGF-1 (liver)
GH is too pulsatile and unpredictable to be accurate.
What would expect IGF-1 to be in acromegaly?
Elevated
Low IGF-1 would indicate no GH to stimulate IGF-1 production –> no acromegaly
Compression of pituitary stalk by a tumor would cause ___
high prolactin due to interrupting flow of DA from hypothalamus that normally inhibit prolactin secretion.
Primary adrenal insufficiency treated with:
glucocorticoid AND mineralocorticoid
Secondary adrenal insufficiency treated with:
glucocorticoid only
Stress dosing: Dose of glucocorticoid should be ____ when patient is sick or under increased physical stress.
doubled/tripled
