Endocrine Flashcards
Systemic hormones involved in hypothalamic negative feedback systems
T3 regulates TRH release
Cortisol regulates CRH
Testosterone, progesterone, and estrogen regulate LHRH
GH and Insulin GF-1 regulate GHRH and GHIH release
Causes of DI
Pituitary surgery (Most common) TBI or SAH
Causes of SIADH
TBI or SAH (most common)
Non-small cell lung CA
Noncancerous lung disease
Carbamazepine (anticonvulsant)
Treatment for SIADH
Fluid restriction
Hypertonic saline if Na
Treatment for DI
DDAVP / Vasopressin
Thyroid gland releases these three hormones
1) T4 (thyroxine) (pro-hormone)
2) T3 (Triiodothyronine) (ACTIVE hormone)
3) Calcitonin
Release of thyroid stimulating hormone from the pituitary tells the thyroid gland to do what two things?
1) Make T4 and T3 (requires iodine)
2) Tells the follicular tissue to make thyroglobulin colloid (does NOT require iodine)
CV effects of hyperthyroidism
Will see an increase in the number and sensitivity of B receptors
- Increased everything heart (HR, inotropy, CO, etc)
- Decreased SVR (B2)
GI effects of hyperthyroidism
DIARRHEA
Metabolic effects of hyperthyroidism
Increased BMR
Utilization of fat stores –> weight loss
Protein breakdown for energy (muscle wasting and weakness)
Release of glucose for energy (increased gluconeogenesis, insulin release, and glucose uptake)
Cause of tremors in hyperthyroidism
Increased sensitivity of neuronal synapses in the spinal cord
Most common cause of hypothyroidism
Hashimoto’s thyroiditis
Diagnosis of hyperthyroidism
High T3 and T4
Low TSH
Diagnosis of hypothyroidism
Low T3 and T4
High TSH
Timing of thyroid storm
Usually 6-18 hours post-op
Can happen in both hyperthyroid AND euthyroid patients
This medication can induce hyperthyroidism OR hypothyroidism
Amiodarone (contains a lot of iodine)
Why is esmolol a good choice for hyperthyroid patients?
They have increased Beta receptors
Short acting
Inhibits the conversion of T4 to T3
MOA and examples of thioamides and what are their SEs?
Examples:
- PTU
- Mathimazole
- Carbimazole
MOA:
- Inhibits TH synthesis by blocking the addition of iodine to the tyrosine residues on thyroglobulin
- Also prevents peripheral conversion of T4 to T3 (like BBs)
- Takes 6-7 weeks to work
- PO form only
Serious SE:
- Hepatitis
- Agranulocytosis
These medications should be avoided in the pt with hyperthyroidism
Anything that activates the SNS!
- Anticholinergics, ketamine, pancuronium, etc
Also avoid hypoxia and hypercarbia because these can stimulate the SNS as well
S/S of thyroid storm
Fever > 38.5C Tachycardia and tachyarrhythmias HTN CHF Shock Confusion and agitation N/V
Under anesthesia, thyroid storm may mimic
MH
Pheochromocytoma
Neuroleptic malignant syndrome
Light anesthesia
Management of thyroid storm
Manage hemodynamics (BBs) Treat fever (active cooling and tylenol) PTU or methimazole (crushed via NGT)
Anesthetic considerations for hypothyroidism
- Risk of airway obstruction (large tongue, swollen cords, possible goiter)
- Delayed gastric emptying
- Hypodynamic circulation (opposite of hyperthyroid)
- Hemodynamic support is best with drugs that improve myocardial performance (i.e- NOT phenylephrine)
- Muscle weakness = sensitivity to NMBs)
- D5NS for glucose and to combat hyponatremia
Aldosterone release is increased by
RAAS Activation
Hyponatremia
Hyperkalemia
Effects of aldosterone in the kidney
Reabsorption of Na
Excretion of K+ and H+
Net effect is increasing intravascular volume
NO effect on osmolarity (this is controlled by ADH)
Physiologic effects of cortisol
Remember, this binds to steroid receptors within the cell to alter DNA transcription and protein synthesis. Takes a while to start working.
THREE BIG THINGS
1) Energy mobilization
- Gluconeogenesis (in liver from amino acids)
- Protein catabolism (to make glucose)
- FFA mobilization (to make glucose)
2) Anti-inflammatory effects
- Stabilizes the membranes of lysosomes, which reduces cytokine release
- Decreased amount of eosinophils and lymphocytes in the blood
3) Increased response to catecholamines
- Improves cardiac performance by increasing the number and sensitivity of Beta receptors on the myocardium
- Cortisol is also needed to BVs to respond well to catecholamines
Also has androgenic effects
Normal cortisol production per day
15-30mg per day
May increase to 100mg per day after major surgery
Cortisol’s mineral/glucocorticoid effects
Has EQUAL glucocorticoid and mineralcorticoid effects
These steroids have the strongest glucocorticoid effects
Dexamethasone and betamethasone
This is the strongest mineralcorticoid
Aldosterone
Also has NO glucocorticoid effect
Cortisol vs. cortisone
Cortisol and cortisone BOTH have equal gluc/min properties.
Cortisone is 0.8x as potent
These glucocorticoids have NO mineralocorticoid effects
Dexamethasone, betamethasone, and triamcinolone
Treatment of Conn’s Syndrome
- Aldosterone antagonist (Spironolactone or elperenone)
- K+ supplementation
- Na+ restriction
S/S of Cushing’s Syndrome
Break it down by cortisol’s clinical effects
1) Glucocorticoid effects
- Hyperglycemia
- Increased risk of infection
- Weight gain
- Osteoporosis
- Muscle weakness (catabolism to make glucose)
- Mood disorder
2) Mineralocorticoid effects
- Think of effects of too much aldosterone, Na reabsorption, and K+ and H+ excretion:
- HTN
- Hypokalemia
- Metabolic alkalosis
3) Androgenic effects
- Women become masculinized
- Men become feminized
Anesthetic implications for Cushin’s disease
- Infection risk
- Position with osteoporosis
- Consider supplemental steroids
- DI may develop after removal of anterior pituitary
Most common cause of Addison’s disease
Chronic steroid administration
S/S of Addison’s disease
Opposite of Cushing’s
- Hypoglycemia
- Anorexia and weight loss
- Fatigue and muscle weakness
- HypoTN
- N/V
- Hyperpigmentation of the knees, elbows, knuckles, lips, and buccal mucosa
Acute adrenal crisis
- Hemodynamic instability and collapse
- Hypoglycemia
- Fever
- Impaired mental status
Treatment of acute adrenal crisis
- Exogenous steroids (Hydrocortisone)
- ECF expansion (D5LR)
- Hemodynamic support
This steroid is given for those who need supplemental steroid peri-op
Hydrocortisone
What does insulin tell the body to do?
Time to store energy!
Released when we eat. So it tells the body we have a surplus, and it’s time to store it for the future.
- Increases uptake into skeletal muscle, liver, and fat
- Glycogen formation
- Fat formation
- Encouraging protein synthesis
Diagnosis of DM
Fasting glucose > 125
Randome glucose level > 200
Two hour plasma glucose > 200 during glucose tolerance test
HbA1C > 6.5
Metabolic syndrome diagnosis
At least 3 of the following:
- Fasting glucose > 110
- Abdominal obesity (>40 inches for men and 35 for women)
- TG > 150
- HDL 130/85
ANS dysfunction in DM
- Painless MI
- Reduced vagal tone –> tachycardia
- Risk of dysrhythmias
- Orthostatic hypoTN
- Impaired compensation to hypoxia and hypercarbia
- Delayed gastric emptying
- Impaired thermoregulation (risk of hypothermia)
- Constipation and diarrhea
Give an example of a biguanide and how do they work? Give some key facts about this class of drugs
Metformin
MOA:
- Inhibits gluconeogenesis
- Inhibits glycogenolysis
- Decreases peripheral insulin resistance
Key facts:
- NO risk of hypoglycemia***
- Discontinue 48 hours prior to surgery
- Risk of acidosis 2/2 increased anaerobic metabolism
- Increased risk of lactic acidosis with drug accumulation (so avoid if liver or renal dz, acute MI, contrast being given, etc)
- May cause vitamin B12 deficiency
- Used for PCOS
Give an example of a sulfonylurea and how do they work? Give some key facts about this class of drugs
Examples:
- Glipizide
- Glyburide
- Glimepiride
MOA:
- Stimulates release of insulin from beta cells
Facts:
- Risk of hypoglycemia!
- Avoid in sulfa allergies
- D/C 48 hours prior to surgery
These classes of oral hypoglycemics do NOT carry a risk of hypoglycemia
- Biguanides
- Alpha-glucosidase inhibitors
- Thiazolidinediones
These are VERY RAPID acting insulins
Lispro
Aspart
Glulisine
All have onset of 5-15 minutes
All peak 45-75 minutes
All have duration of 2-4 hours
Insulin resistance occurs once daily insulin requirement excess ____ units/day
100
These drugs make insulin induced hypoglycemia even worse
MAOIs
ASA
Tetrycycline
Common S/S of carcinoid syndrome
If carcinoid hormones are NOT cleared by the liver, then they cause:
- Flushing and diarrhea (Most common!!)
From histamine:
- Bronchoconstriction
- Vasodilation (flushing)
- HypoTN
From kinins and kallikrein:
- Bronchoconstriction
- Vasodilation and flushing
- HypoTN
- Exacerbates histamine release
From serotonin:
- Bronchoconstriction
- Vasoconstriction
- HTN
- SVT
- Increased GI motility
S/S of carcinoid crisis
Tachy
HTN or HypoTN
Intense flushing
Abd pain and diarrhea
Drugs to give and avoid in carcinoid patients
GIVE:
- Somatostatin (Octreotide)
- Antihistamines
- Serotonin antagonists
- Steroids
- Pressors for hypoTN (phenylephrine and vasopressin)
AVOID:
- Histamine releasing drugs
- Sux (fasciculations can cause hormone release from tumor)
- Exogenous catecholamines may worsen hormone release
- Anything that stimulates the SNS (ephedrine and ketamine)
When is GH released?
- Fasting
- Hypoglycemia
- Decreased FFAs
- Increased amino acids
- Sleep
- Stress and anxiety
- GHRH from pituitary
- Dopamine
- Estrogen
- Alpha agonists
Most common cause of cushing’s syndrome
Chronic glucocorticoid therapy
Effects of GH (somatotropin)
- Facilitates growth everywhere in the body
- Increases protein synthesis
- Enhances use of FFAs for energy
