Endocrine Flashcards
Causes of elevated or depressed hormone levels
Failure of feedback systems
Gland dysfunction
Gland is releasing too much or too little
Increased hormone degradation or inactivation
Ectopic hormone release
Secretory cells unable to obtain, produce, or convert hormone precursors
Ways the target cell can fail
Not enough receptors on cell surface
Impaired receptor function
Antibodies produced against the receptors (Hashimoto’s thyroiditis)
Antibodies mimic hormone action
Unusual expression of receptor function (more genetic, or may occur in tumor cells)
For someone to be diagnosed with SIADH, they must have
normal thyroid and adrenal function, because thyroid hormone and glucocorticoids are essential for free water clearance by the kidneys. Meaning, if these glands weren’t functioning, it would also cause water retention.
The posterior pituitary makes
ADH and oxytocin
Symptoms of SIADH
Causes water retention, hyponatremia, and hypoosmolarity
Cause of SIADH
Hypersecretion of ADH, usually from an ectopic source (small cell lung carcinoma)
Types of DI
1) Neurogenic
- Low ADH release from posterior pit
- tumors, hypophysectomy, head trauma
2) Nephrogenic
- Normal ADH levels, but the kidney fails to respond
- d/t drugs or diseases that damage the renal tubules
Either way, causes total or partial inability to concentrate urine, and people get pretty damn dehydrated
The brain is able to autoregulate between these MAPs
50-150
Causes of pituitary infarction
Sheehan syndrome (post-partum hemorrhage)
Hemorrhage
Shock
Causes of anhypopituitarism
Usually due to a cell DESTROYING tumor (or by head trauma or infections)
Panhypopituitarism causes a decrease in release of these hormones
ACTH
TSH
LH and FSH
GH
This causes hypothyroidism, low cortisol (unable to handle stressors), and depressed sex hormone production. Results in lethargy, weight gain, and loss of all sexual function.
Hyperpituitarism cause and manifestations
Usually caused by a benign, slow-growing pituitary adenoma that compresses the pituitary.
S/S
- HA and fatigue***
- Visual changes***
- Hyposecretion of neighboring hormones.
Usually, pituitary adenomas cause increased secretion of
GH and prolactin. Paradoxically, they will decrease the release of neighboring hormones
Acromegaly
Caused by a GH secreting pituitary adenoma. Causes connective tissue proliferation, thickening of bones and articular cartilage, narrowing of joint spaces, coarse skin and hair, enlarged bones of the face, hands, and feet
Are those with dwarfism able to reproduce?
Only about 1/3 of them.
2/3 will NOT develop sexually d/t the lack of GH.
What is the most common form of hyperthyroidism?
Grave’s disease
Patho of Grave’s disease
TSIs (thyroid stimulating immunoglobulins) bind to TSH receptors, causing continual cAMP production. All this stimulation will increase T3 and T4 levels and decrease TSH levels.
TSIs have a (longer/shorter) half-life than TSH
Longer (12 hours). TSH is only about 1 hour.
Should we check thyroid hormone levels before we take someone with thyroid problems back to the OR?
YES! We do no want hyperthyroidism during surgery!!
Is exophthalmos reversible with treatment?
No :(
Causes of hypothyroidism
1) Autoimmune (Hashimoto)
2) Lack of iodine
3) Idiopathic causes (deficiency of enzymes needed to make T3 and T4)
4) Thyroid resection
5) Radiation to the thyroid
Treatment for hypothyroidism
Levothyroxine Iodine (if the cause if iodine deficiency)
Hashimoto’s thyroiditis
T cells become sensitized to thyroid antigens. Th cells tell CD8 cells to destroy the thyroid cells, and they also tell B cells to make plasma cells with antibodies that will bind to and inhibit TSH receptors (anti-TSH receptor antibodies)
What is myxedema?
A severe form of hypothyroidism.
Causes chondroitin and hyaluronic acid to build up between the connective fibers of the skin, resulting in boggy edema, especially around the eyes, hands, and feet.
Also causes thickening of the tongue and laryngeal/pharyngeal mucus membranes.
What type of intubation would we probably do if our patient’s voice is hoarse?
Awake intubation
Cause of cretinism
Hypothyroidism in fetal life, early infancy or childhood. Caused by
1) Failure of thyroid gland to develop
2) Lack of thyroid hormone
3) Lack of iodine
TH is essential for embryonic development, especially for the brain. Causes MR if not treated
What happens in cretinism?
Skeletal growth is stunted more than soft tissue growth
- Causes growth stunting, obesity, large tongue, etc.
Two types of hyperparathyroidism
1) Primary
- Excess PTH release
- D/t adenoma or hyperplasia
2) Secondary
- High PTH due to chronic diseases that cause low calcium or high phosphate
- ESRD or malabsorption syndromes
How does hypoparathyroidism cause hypocalcemia?
The osteoclasts become almost totally inactive and there is almost no tubular Ca++ reabsorption. This causes decreased Ca++ levels.
What major thing does hypocalcemia put you at risk for??
Laryngospasm!
Treatment for hypoparathyroidism
PTH and vitamin D
Causes of Cushing’s Syndrome
1) Pituitary tumor (most common)
2) Adrenal tumor
3) Paraneoplastic (ACTH secretion from outside the pituitary like in small cell)
4) Iatrogenic (exogenous corticosteroid use)
Cushing’s syndrome is usually caused by elevated levels of
ACTH from the pituitary (caused by microadenoma)
Conn’s disease is usually caused by tumors located where?
Zona glomerulosa (part of the adrenal cortex where aldosterone is made)
Fluid/electrolyte changes associated with Conn’s syndrome
Hypervolemia, hypernatremia, hypokalemia, and metabolic alkalosis.
Patient will be very fluid overloaded and hypertensive, but not edematous (due to the effects of sodium escape phenomenon).
Causes of Addison’s disease (adrenocortical insufficiency)
1) Primary atrophy (autoimmune)
2) Injury to the adrenal cortex
Both cause a decrease of BOTH corticosteroids (glucocorticoids and mineralcorticoids)
Depletion of aldosterone: Hyponatremia, hypovolemia, hyperkalemia, mild acidosis, low BP and CO.
Depletion of cortisol: Low BG, decreased metabolic function, decreased ability to respond to stressors
