Basic ENDO/Metabolic Flashcards
Glucagon is secreted by pancreatic alpha cells in response to hypoglycemia and INHIBITS (Gluconeogenesis/Glycolysis) to IMPROVE blood glucose concentration
Glycolysis
*glucagon STIMULATES glycogenolysis and gluconeogenesis
Glucagon raises blood sugar indirectly how? (3)
- Stimulates lipolysis
- produces glycerol and FFA - Inhibits Glycolysis
- stops consumption of glucose - Inhibits glycogen synthesis
- available glucose can be released into bloodstream instead of being stored in liver
How does glucagon affect the heart?
inotropic and chronotropic effects
How to differentiate Malignant hyperthermia from Thyroid storm?
- Muscle rigidity
- Rate of EtCO2 ( MH»_space; TS)
- Temperature (MH»_space; TS)
- MH (hyperkalemia), TS (hypokalemia)
Treatment for MH vs Thyroid storm?
MH: Dantrolene
Thyroid storm: Sodium iodide and PTU
AVP (aka ADH) regulates diuresis and antidiuresis. The most potent trigger for its release is ____
systemic arterial hypotension (mediated by aortic and carotid baroreceptors)
-> AVP vasoconstricts by stim V1a receptors
AVP (aka ADH) acts on receptors in the collecting ducts to induce water and Na reabsorption that causes what changes to urine and plasma osmolality?
Increases urine osmolality
Decreases plasma osmolality
Why are clinically hypothyroid pts susceptible to hypotensive effects of anesthesia?
- Decreased CO
- Blunted autonomic reflexes
- Decreased Intravascular volume
Primary vs secondary hypothyroidism
- TSH, T4
- primary dysfunction?
Primary
- High TSH, low T4
- primary dysfunction: lack of T4 feedback on pituitary (ie: hashimotos, iodine deficiency)
Secondary
- Low TSH, Low T4
- primary dysfunction: pituitary gland (ie: adenoma, hemorrhage, radiation)
What is a bad idea for management of pts with thyrotoxicosis (hypermetabolic state d/t Thyroid hormone?
RAI
- destroys thyroid gland - can worsen thyrotoxicosis bc thyroid hormone is released into the blood
What can you pretreat hyperthyroid pts with prior to RAI to prevent thyrotoxicosis (aka thyrostatic medications)?
Methimazole or propanolol
What is the treatment for Hashimotos (thyroid gland is attacked by immune system)?
L-thyroxine (levothyroxine)
*pts are hypothyroid
What is the treatment for Graves disease (thyroid gland is hyperfunctioning)?
Methimazole, or PTU, or Iodide
*Pts are hyperthyroid
Why are pts hyperglycemic after surgery/stress?
Body release hormones (cortisol, catecholamines, glucagon) that are counter-regulatory to insulin -> insulin resistance –> increase production and release of glucose
Diabetic autonomic neuropathy results in resting tachycardia that does NOT compensate well for changing hemodynamics, which can cause ______
orthostatic hypotension
Why is starting a BB prior to a-blocker dangerous in pts with pheochromocytoma?
Hypertensive emergency
- unopposed alpha vasoconstriction
Ideally: initiate a-adrenergic receptor antagonist (phenoxybenzamine, phentolamine, doxazosin, terazosin, or prazosin) 10-14 days prior to and including morning of surgery.
- can add BB only if indicated (persistent tachycardia, hypertension, dysrhythmias)
In DKA pts, what is recommended once plasma glucose is approximately down to 200 mg/dL?
Switch from 0.45% NaCl to D5 in 0.45% NaCl
________ is the combination of euvolemia, hypotonic plasma (low serum osm), hypertonic urine (urine osm > 100mOsm), and high urine sodium (>20 mEq/L).
Hallmark of SIADH
- Hypotonic plasma d/t increased free water retention from ADH
INAPPropriate ADH
- Increased NA in the PP
ADH is released from the _______ in response to _____
Posterior pituitary
Hyperosmolar state or hypovolemia
ADH can be inappropriately be released by ______
- Stress
- Major trauma
- Severe pain
- Use of opioids
- Sepsis
- Nausea
Primary hyperaldosteronism (Conn syndrome) is most commonly caused by _____
unilateral adrenal adenoma
- mineralocorticoid excess (aldosterone)
________ increases the reabsorption of Na and secretion of K in the distal tubule for volume expansion. What happens to Na and K if a pt has hyperaldosteronism?
Aldosterone
- Hypernatremia
- Hypokalemia
- (Metabolic alkalosis)
Stress dosing steroids.
- Low risk for pts taking < ____
< 5 mg prednisone
*conflicting data on superiority
Steroid Trivia
- Mineralocorticoids regulate
- Glucocorticoids regulate
- Corticosteroids regulate
- Mineralocorticoids regulate: sodium and water levels (aldosterone)
- Glucocorticoids regulate: metabolism and inflammation (cortisol)
- Corticosteroids regulate: both gluco/mineralocorticoid effects
Adrenal cortex three diff layers and what they secrete
- Outer: zona glomerulosa
- Mineralocorticoids (aldosterone) - Middle: zona fasiculata
- Glucocorticoids (cortisol) - Inner: zona reticularis
- Gonadocorticoids
Adrenal medulla is made of ______ and secretes ____
chromaffin cells
catecholamines (adrenaline, noradrenaline)
Best way to intraoperatively manage diabetic pt’s insulin pumps
Continue at programmed rate in uncomplicated surgery
If complicated surgery/expecting large hemodynamic shifts, electrolyte imbalances, and acid-base balance, turn OFF basal rate, and start continuous insulin infusion
_____ is the most common cause of hyponatremia in pts with CNS disturbances
SIADH
What condition looks exactly like SIADH, but is treated differently?
- Hyponatremic (<280)
- High ur Na (>40)
- High ur Osm (>100)
Cerebral salt wasting
*Cerebral salt wasting is either euvolemic or hypovolemic
In SIADH: treatment is fluid restriction, PO NaCl, Lasix
What type of acid base disturbances do loop and thiazide diuretics cause?
Hypochloremic metabolic alkalosis
What type of electrolyte is needed in the treatment of alkalosis?
Potassium
- since alkalosis causes hypokalemia
- K+ is driven into cells and exchanged for intracellular H+ in attempt to buffer alkalosis
Most pts with primary hyperparathyroidism are asymptomatic, but what is the most common presenting symptom if any?
nephrolithiasis
- secondary to elevated calcium levels
Aldosterone (mineralocorticoid) and cortisol (glucocorticoid) promote renal potassium (uptake/secretion)
secretion
- hypokalemia
Insulin and thyroid hormones promote cellular potassium (uptake/secretion)
uptake
- hyperkalemia
What happens to Na and K with glucocorticoid administration?
Stimulate Na reabsorption and K excretion
- Hypernatremia and hypokalemia
How to change the non-depolarizing neuromuscular blocker in pts with hyperparathyroidism?
Increase the dose
- Hypercalcemia antagonizes effects of non-depolarizing NMB
How can hyperparathyroidism lead to respiratory insufficiency?
Hypercalemia is assoc w/ muscle weakness
Most common cause of stridor 24-96 hours post thyroidectomy?
hypocalcemia
*recurrent laryngeal n damage is more likely to cause early stridor and difficulty with phonation
Why does damage to the superior laryngeal n cause change in pitch of pts voice?
SLN innervates cricothyroid muscle
The normal pulse rate variability that occurs with inhalation and exhalation is 10/min. Baroreceptors sense changes to preload with inspiration -> increase pulse rate, and expiration -> decrease rate.
Loss of this variability is a sign of _____
early autonomic neuropathy.
(T3/T4) exerts direct effects on the myocardium and may result in thyrotoxic cardiomyopathy
T3
In primary hyperthyroidism, what levels are increased and decreased (TSH, T3, T4, THBR)
TSH: decreased
T3 and T4: increased
Thyroid hormone binding ratio (amt of free T4 circulating): increased
*The hormones themselves are affected
Most common initial presentation of pts with primary hyperaldosteronism?
- hypokalemia metabolic alkalosis
- urinary loss of K+ and H+ in exchange for absorbing Na+ - Increased BP
- Reduced renin
MEN I tumors
Pituitary tumor
Parathyroid tumors
Pancreatic tumors
MEN IIa tumors
Parathyroid tumors
Thyroid tumor (medullary)
Pheochromocytoma
MEN IIb tumors
Ganglioneuromas
Parathyroid tumors
Thyroid tumor (medullary)
Pheochromocytoma
Glucagon release is triggered by (hyper/hypoglycemia) and its release is stimulated by ______
Hypoglycemia
- indicated in cases of insulin overdose
Epinephrine (catecholamines)
________ are the most effective drugs to block release of thyroid hormone from the thyroid gland
Iodides, but should only be used after a thyrostatic agent is given (ie: PTU or methimazole) d/t the “escape phenomenon” where new thyroid hormones are actually synthesized and worsen the hyperthyroidism
________ consists of episodic flushing, diarrhea, wheezing and R sided heart disease
carcinoid syndrome
Pancuronium (stimulates/blunts) the sympathetic nervous system
stimulates
- use with caution in pts with hyperthyroidism
When can you stop BB in hyperthyroid pts getting thyroidectomy
several weeks
- half life of T4 is 7-8 days
Primary adrenal insufficiency (addison disease) is characterized by: (5)
- Hyponatremia
- Hyperkalemia
- Metabolic acidosis
- Hyperpigmentation
- Hypocortisolism
Primary adrenal insufficiency develops adrenal gland dysfunction/exacerbation. What is treatment?
100mg IV hydrocortisone q6h for 24hrs
*adrenal gland is unable to produce sufficient mineralocorticoid, glucocorticoid, and androgens
Primary vs secondary disorders
Primary: something affects the production or quantity or quality of the hormone itself
Secondary: Something disrupts the hormone axis that is usually able to respond to fluctuating hormone level
Destruction of ___% of the adrenal glands must occur before clinical signs of adrenal insufficiency appear
> 90%
Type 1 diabetes occurs d/t injury to ____ in the pancreaas
Beta cells, responsible for insulin production
Statins are _____ inhibitors. Which
HMG-CoA reductase inhibitors
- increase HDL:LDL
How does metformin help control blood sugars in pts with diabetes?
Decreases hepatic gluconeogenesis and increases insulin sensitivity
Malignant hyperthermia is closely associated to which 3 diseases?
- Central core disease
- Multi-minicore disease
- King-Denborough syndrome
Lipolysis will increase or decrease with:
- alpha 2 stimulation
- beta 2 and 3 stimulation
- alpha 2 stimulation: inhibit
- beta 2 and 3 stimulation: stimulate
Benefits of carbohydrate rich drinks given 2h before surgery ?
increases insulin sensitivity (decrease insulin resistance)
Stress of sx = hyperglycemia
Fasting state = low insulin
What catecholamine predominates in this type of pheochromocytoma?
- Paroxysmal
- Sustained
Paroxysmal: EPi
Sustained: Norepi
How does a pt’s insulin regimen get affected perioperatively if they are on:
- Rapid/short acting:
- Intermediate:
- Long acting:
Rapid/short acting:
- continue
Intermediate:
- take 75% nl dose night before sx
- take 50% nl dose day of sx
Long acting:
- take 50% nl dose morning of sx
Concern about pts on chronic glucocorticoid therapy?
Can suppress the hypothalamic-pituitary adrenal axis ->
insufficient response by adrenal glands to the stress of major sx
Categories of risk of adrenal insufficiency: (what dose of steroids are they on)
Low
Intermediate
High
Low:
- Any dose GC < 3 weeks
- Prednisone <5mg/d or 10mg q other day
Intermediate:
- Prednisone 5-20mg/d > 3 weeks
- Chronic inhaled or topical GC
High:
- Cushing syndrome 2/2 to GC
- Prednisone >20mg/d > 3 weeks
*High risk pts should be considered for periop stress dose steroids
During a stress response (ie. surgery), which hormones decrease?
T3/T4
Growth RELEASING hormone
*almost every other hormone increases or stays same
Insulin effects on:
Adipocytes
Increase glucose uptake
Increase Fatty acid storage/synthesis
*insulin has primarily anabolic effects and inhibits catabolic processes
Insulin effects on:
myocytes
Increase glucose uptake
Increase amino acid uptake
Increase glycogen storage
Increase protein synthesis
*insulin has primarily anabolic effects and inhibits catabolic processes
Insulin effects on:
Hepatocytes
Increase macronutrient uptake
Increase Fatty acid storage/synthesis
Increase glycogen synthesis
*insulin has primarily anabolic effects and inhibits catabolic processes
During surgical stress, the body enters a state of insulin resistance d/t what?
release of stress hormones (catecholamines, cortisol, glucagon)
insulin has primarily ______effects and inhibits ______ processes
anabolic
catabolic
Glucagon STIMULATES _______ and _______
glycogenolysis
- break down glycogen to glucose
gluconeogenesis
- glucose synth by liver
*both improve blood glucose [ ]
How does glucagon affect gastric motility and biliary sphincter and lower esophageal sphincter tone?
DECREASE
Lab derangements with corticosteroid use
- Leukocytosis
- Polycythemia
- Hyperglycemia
- Mild hypernatremia
- Hypokalemia
- Hypercalciurea
Insulin is secreted by ____, and is metabolized by _____
B-islet cells of pancreas
Kidneys and liver
How does hyperparathyroidism affect neuromuscular blockers?
Hypercalcemia Antagonizes nondepolarizing NMBs
- need to increase dose of Roc
Which cell is MOST dependent on insulin for the majority of the cells’ glucose uptake?
Cardiac myocyte
(Remember insulin's effects on myocytes: Increase glucose uptake Increase amino acid uptake Increase glycogen storage Increase protein synthesis)
Which cells are dependent on insulin for the majority of glucose uptake?
- Hepatocytes
- Immune cells
- Erythrocytes
- Brain neurons
- Cardiac
*Cardiac cells are MOST dependent on insulin for the majority of the cells’ glucose uptake?
Which foods are associated with a latex allergy?
- Avocados
- Bananas
- Chestnuts
- Kiwi
- Papayas
- Potatoes
- Tomatoes
The majority of latex allergies are d/t what type of reaction?
Irritant contact dermatitis
*NOT d/t immune mediated hypersensitivity reactions
If you suspect a pt is having a latex allergy, what lab should be drawn?
serum mast cell tryptase level w/in 15-60min and again after 24 hr
- Increased if +
Primary vs secondary disorders
Primary: something affects the production or quantity or quality of the hormone itself
Secondary: Something disrupts the hormone axis that is usually able to respond to fluctuating hormone level
(Hyperthyroidism / Hypothyroidism) is more commonly associated with pleural effusions
Hypothyroidism
Hyperthyroidism is associated with hematologic effects?
Anemia
Thrombocytopenia
Insulin and glucagon utilizes the ____ pathway within the _____
cAMP signaling
hepatocyte
Which cells in the body specifically use the Inositol triphosphate-3 (IP-3) second messenger pathway?
Cardiac myocytes
- increase cytoplasmic calcium ions -> activates ryanodine receptor on sarcoplasmic reticulum -> calcium induced calcium release form SR
How does cortisol directly influence potassium homeostasis?
- Enhances sodium and potassium exchange
- Enhances renal potassium secretion
Etomidate inhibits the synthesis of cortisol transiently and should be avoided in pts with ______
adrenal insufficiency
- ie: addison disease aka primary adrenal insufficiency
- adrenal glands unable to produce sufficient quantities of glucocorticoid
What happens in secondary adrenal insufficiency?
failure in adequate production of CRH or ACTH secondary to hypothalamic/pituitary disease or suppression
*Unlike Addison disease, there is only glucocorticoid deficiency with secondary disease
