Term
| What is the axis of command for thyroid hormone secretion, including negative feedback mechanism. |
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Definition
Hypothalamus secretes TRH --- TRH stimulates TSH release from Pituitary --- TSH stimulates T3 & T4 synthesis and secretion.
* Elevated T3 & T4 feedback ---hypothalamus & pituitary decrease further TRH & TSH release. |
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Term
What are 3 signs/symptoms of hyperthyroidism?
What are 3 causes of hyperthyroidism? |
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Definition
Cause: over exposure to T3 & T4
Graves
thyroiditis
excess TSH (from tumors)
exogenous hyperthyroidism
ectopic thyroxine production - teratoma
follicular thyroid carcinoma
Signs/Symptoms:
young, nervous, grumpy, perspiration, heat intolerance, weight loss, eye symptoms - bulging eyes, tachy cardia, goiter, smooth - velvety skin. |
|
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Term
| What is the molecular mechanism that causes the hyperthyroid state in Graves disease? Why doesn't the normal negative feedback mechanism work to regulate the thyroid hormone levels? |
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Definition
| thyroid stimulating antibodies bind to TSH receptors (unknown cause) and the thyroid becomes unregulated. |
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Term
3 signs/symptoms of hypothyroidism.
Causes of primary and secondary hypothyroidism. |
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Definition
signs/symptoms: cold intolerance, weakness, muscle cramps, aching, hoarseness, decreased hearing, mild weight gain, edema of eyelids/hands/feet, bradycardia.
Causes:
Primary - insufficient amount of functional tissue
Secondary - disease of the pituitary & hypothalamus causing thyroid stimulating release.
Drug - lithium carbonate (used for manic depression) |
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Term
| Why is congenital hypothyroidism so important to diagnose early? |
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Definition
| Because creatinism can occur within weeks/months of birth without treatment. |
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Term
Thyroid nodules:
a) features of the thyroid that favor benign or malignant nodule
b) patient characteristics (age,gender,history) that favor B9 or malignant nodule.
c) significance of hot or cold nodules on radioactive iodine uptake scan. |
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Definition
- Bellow age 40 greater risk of malignancy
-Children, 50% are malignant
- Rate of growth, faster is worse
Cold nodules have malignant potential
Hot nodules are usually B9 |
|
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Term
| 4 types of thyroid cancer - what age groups get them? |
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Definition
1) Papillary (75-85%) 35 yrs
2) Follicular (10-20%) 35 yrs
3) medullary (5%) 53 yrs
4) anaplastic (rare) >70 yrs
* earlier the age the better the prognosis. |
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Term
| How do parathyroid glands respond to blood calcium levels? |
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Definition
| they respond directly to the amount of ionized calcium in the blood, when blood calcium drops, the parathyroid secretes PTH which goes out into the body and acts at several sites to raise levels. Once calcium levels are restored, the calcium shuts off PTH secretion - a classic negative feedback loop. |
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Term
3 major sites/organs that PTH acts on.
What does it do at each site? |
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Definition
BONES- stimulates bone resorption, mobilizes CA++
KIDNEYS - increases tubular reabsorption & increases Vitamin D synthesis
INTESTINES - Increased vitamin D-dependant Ca++ absorption in small bowel. |
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Term
| Main causes of primary and secondary hyperparathyroidism. |
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Definition
Primary- excessive PTH in absence of appropriate stimulus, so PTH will be high even though there's adequate calcium.
***one of the most common endocrine disorders***
Secondary:
"appropriately excessive" secretion of PTH in response to chronic hypocalcemia. Cause is renal disease and/or vitamin D deficiency. |
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Term
| Size of 4 PT glands if hyperparathyroidism is due to adenoma or to hyperplasia. |
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Definition
-Adenoma- solitary, weight >5 grams, round, remaining 3 glands shrunken due to neg. feedback from overactive adenoma.
-Hyperplasia - all 4 glands effected, total weight <1 gram
-Parathyroid carcinoma - solitary may be >10 grams |
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Term
| What is hypercalcemia of malignancy? Does feedback inhibition play a role? |
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Definition
A tumor is producing protein that resembles PTH.
No! There is no feedback to shut it down since it is an abnormal hormone that is not responsive to calcium levels. |
|
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Term
| Name the types of tumors that could make PTH related peptides. |
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Definition
-small cell lung carcinoma
-breast carcinoma
-renal carcinoma
-prostate carcinoma |
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Term
| What is the most common cause of hypoparathyroidism? Other causes? |
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Definition
MC: Thyroid or neck surgery with removal of the parathyroid glands.
Other: congenital absence, primary atrophy (autoimmune disease), familial hypopararthyroidism. |
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Term
Symptoms of hypoparathyroidism?
Other organs effected? |
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Definition
MC are neuromuscular excitability and tenacity due to decreased blood calcium levels.
Others: brain, eyes, heart, and in kids - teeth. |
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Term
| Lab results show decreased T4 and increased TSH - this would indicate? |
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Definition
|
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Term
| Elevated T3 & T4 with decreased TSH indicates? |
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Definition
| Hyperthyroidism. TSH is decrease due to negative feedback inhibition. |
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Term
| What has a better prognosis, inherited or non-inherited medullary thyroid carcinoma? |
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Definition
|
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Term
Symptoms of hyperparathyroidism:
painful__________(due to weakening)
abdominal_______(due to GI disturbances)
psychic__________(due to multiple nervous system alterations) |
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Definition
painful bones
renal stones
abdominal groans
psychic moans |
|
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Term
| 2 most common forms of hyperthyroidism |
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Definition
|
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Term
| What is the physical marker you can see during a physical exam of a patient with a goiter? |
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Definition
| When they swallow, the thyroid moves while other structures do not. |
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Term
| Currently the most common cause of hypothyroidism in the US? |
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Definition
| 2nd stage of hashimoto's (degenerated) |
|
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Term
| What is Sheenana's syndrome? What causes it? |
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Definition
infarction of pituitary glad.
Happens to mom during L&D |
|
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Term
| What is the most common type of nodule in the thyroid? |
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Definition
|
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Term
| Is it more common to see an adenoma or adenocarcinoma in the thyroid? |
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Definition
|
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Term
Thyroid:
Bilateral nodules are likely to be____________
Single nodules are likely to be_________ |
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Definition
bilateral - goiter
single- neoplasm |
|
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Term
| What is the #1 risk factor for Thyroid CA? |
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Definition
| Radiation, nuclear accidents (Russians) |
|
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Term
| What is the most common Thyroid CA? |
|
Definition
|
|
Term
|
Definition
| young male who's had exposure to radiation |
|
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Term
| What is the survival rate from Thyroid CA? |
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Definition
|
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Term
| Where does follicular CA spread to? |
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Definition
BONE
-also-
Prostate
Breast
Lung
Kidney |
|
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Term
| Which is the most lethal thyroid ca? What does it affect? Prognosis? |
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Definition
| Anaplastic. Invades the trachia - death occurs w/in one month. |
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Term
| What are the products of the adrenal cortex and medulla |
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Definition
Adrenal cortex:
The cortex contains 3 functional layers:
zona glomerulosa secretes aldosterone,
zona fasciculata secretes cortisol,
zona reticularis secretes the sex hormones (estrogens and androgens)
Medulla: produces catecholamines (epinephrine & norepinephrine) |
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Term
| What is the the hypothalamic-pituitary-adrenal gland hormonal axis and feedback inhibition |
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Definition
The major glucocorticoid, cortisol which helps to regulate catabolism (breakdown of tissue) is
produced by the cortex of the adrenal gland (the outer rim) and are under the influence from the
pituitary derived hormone, adrenocorticotropic hormone (ACTH), which is in turn, modulated by
the hypothalamic secretion of corticotropin releasing hormone CRH. It is under a similar
feedback inhibition as seen in the thyroid
The hypothalamic-pituitary-adrenal axis of command is modulated by the level of need for cortisol and other hormones produced by the adrenal gland. If levels are adequate or too high, both CRH and ACTH are reduced which then reduces the amount of production in the adrenal gland itself. Cortisol inhibits the uptake of glucose in most tissues, reduces the reabsorption of calcium and phosphorus in the kidney and suppresses the immune system to some degree. |
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Term
| What is the dexamethasone suppression test |
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Definition
The theory of the test is that small doses of a potent glucocorticosteroid - dexamethasone inhibit the release of ACTH (the normal negative feedback loop) and thus there is decreased production of
cortisol. Dexamethasone does not interfere with the testing for levels of cortisol or its breakdown products, so if there is an actual fall of cortisol, it will be detected. It is usually an overnight study: the patient takes the dexamethasone at 11 pm to midnight and the levels of cortisol are drawn the next morning. If the cortisol is elevated then the diagnosis of hypercortisolism is confirmed. |
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Term
What are the differences, causes and how to detect the different adrenal insufficiencies. What is the
clinical presentation of hypoadrenalism? |
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Definition
To check the difference between primary or secondary hypoadrenalism, you can check the serum ACTH levels.
Elevated in primary
Decreased in secondary
Presentation for hypoadrenalism:
Primary: weakness, fatigue, vomiting, anorexia, hyperpigmentation
Secondary: same signs as primary, except w/out hyperpigmentation |
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Term
| What is primary hyperalderostonism? And what causes it? How is it diagnosed? |
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Definition
-It is a clinical syndrome characterized by autonomous hypersecretion of aldosterone
-It is caused by a variety of causes. The hypersecretion of aldosterone becomes independent of the renin-angiotensin system which normal regulates the output of aldosterone. It is characterized by suppression of plasma renin activity (feedback inhibition), low potassium, sodium retention and hypertension.
It can be caused by a solitary aldosterone-producing adrenocortical adenoma, or by bilateral
hyperplasia is another cause of primary hyperaldosteronism.
-The diagnosis of primary hyperaldosteronism is made by the elevated levels of aldosterone and depressed renin in the circulation. |
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Term
| What is a pheochromocytoma? Where is it located in the adrenal gland? What does it produce? What is the clinical presentation, tests for diagnosis, treatment? |
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Definition
What: This is typically a tumor
Where: the adrenal medulla.
Produces: Excessive catecholamines by tumors in the adrenal medulla or extra-adrenal sites leads to a rare, but surgically-treatable, form of hypertension.
Presentation: fourth to fifth decade, Headache, sweating, tremor,
visual disturbances, abdominal pain, and nausea also occur. The episodes may be induced by
emotional stress, exercise, changes in posture and palpation in the region of the tumor. |
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Term
| What are other benign and malignant masses of the adrenal? |
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Definition
Benign masses include: cortical adenomas, cysts, hermorrhages, and granulomas (an nodule of
inflammatory cells - macrophages). Small non-functioning benign-appearing lesions (2.5 cm) should be followed with CT to note enlargement in 6-12 months. Any increase in size dictates removal. If unchanged over a year, it is unlikely to be malignant.
Malignant nonfunctioning tumors include metastatic tumors and adrenal adenocarcinomas (quite rare). Functioning tumors should be assessed for which hormone is produced, which we have
covered today: Cushing's syndrome, aldosteronoma (primary hyperaldosteronism), pheochromocytomas, and lastly, which we did not cover: virilizing tumors (over production of testosterone or estrogen). |
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