APPLIED PHYSIOLOGY | Endocrine Function and Anesthesia Flashcards
TRUE or FALSE
Patients who have received corticosteroids for more than 3 weeks in the past year may have adrenal suppression
True
What is the most potent endogenous glucocorticoid?
Cortisol (Hydrocortisone)
Which of the following is considered to be the daily production of endogenous cortisol?
A. 10 mg
B. 15 mg
C. 20 mg
10 mg
Most of the circulating hormone is bound to the α-globulin cortisol-binding globulin. It is the relatively small amount of free hormone that exerts the biologic effects.
Endogenous glucocorticoids are inactivated primarily by the liver and are excreted in the
urine as 17-hydroxycorticosteroids.
TRUE or FALSE
cortisol secretion is decreased in the elderly patient?
TRUE
cortisol secretion is decreased by approximately 30% in the elderly patient.
What is the most potent regulator of ACTH
secretion?
A. Cortisol
B. Vasopressin
C. Aldosterone
A. Cortisol
Cortisol is the most potent regulator of ACTH
secretion, acting by a negative-feedback mechanism to maintain cortisol levels in a physiologic range.
ACTH release follows a diurnal pattern, with maximal activity occurring soon after awakening
Which of the following is the most potent vasopressor produced in the body?
A. Angiotensin II
B. Epinephrine
C. Dopamine
D. Aldosterone
A. Angiotensin II
Angiotensin II is the most potent vasopressor produced in the body. It directly stimulates the
adrenal cortex to produce aldosterone.
What is the most common cause of Cushing syndrome?
A. adrenal carcinoma
B. neuroendocrine tumors
C. prolonged exogenous glucocorticosteroid use
C. prolonged exogenous glucocorticosteroid use
Overall, the most common cause of Cushing syndrome is the prolonged administration of exogenous glucocorticoids to treat a variety of illnesses.
What is the maintenance dose of fludrocortisone (9-α-fluorohydrocortisone) after bilateral adrenalectomy?
A. 0.05 to 0.1 mg/d
B. 0.5 to 1 mg/d
C. 0.1 to 0.5 mg/d
A. 0.05 to 0.1 mg/d
After bilateral adrenalectomy, most patients require 0.05 to 0.1 mg/d of fludrocortisone (9-α-fluorohydrocortisone) starting around day 5 to provide mineralocorticoid activity.
Slightly higher doses may be needed if
prednisone is used for glucocorticoid maintenance because it has little intrinsic mineralocorticoid activity.
Cathecolamines are synthesized from?
A. endoplasmic reticulum
B. cytoplasm
C. Mitochondria
A. Rough endoplasmic reticulum
Catecholamine prohormones are synthesized in the rough endoplasmic reticulum of the chromaffin cells.
What β-blocker decreases peripheral conversion of T4 → T3?
A. Esmolol
B. Propranolol
C. Labetalol
B. Propranolol
The best β-blocker for thyroid storm is propanolol. Second choice is esmolol.
MOA:
TRUE or FALSE
Hyperthyroid patients are unlikely to be regulated to a euthyroid state with antithyroid drugs alone in
less than 6 to 8 weeks.
Why?
TRUE
Normal thyroid glands usually contain a
store of hormone that is large enough to maintain a euthyroid state for several months, even if synthesis is abolished. Therefore, hyperthyroid patients are unlikely to be regulated to a euthyroid state with anti-thyroid drugs alone in
less than 6 to 8 weeks.
Keyword: 6 - 8 WEEKS!
What is the role of steroid perioperatively?
What is the dose?
Glucocorticoids such as dexamethasone (8 to 12 mg/d) are used in the management of severe
thyrotoxicosis because they reduce thyroid hormone secretion and the peripheral conversion of T4 to T3.
PERIPHERAL CONVERSION of T4 to T3.
8 - 12 mg/d
TRUE or FALSE
Radioactive iodine crosses the placenta.
TRUE
It should not be administered to patients who
are pregnant because it crosses the placenta and may destroy the fetal thyroid.
TRUE or FALSE
Anti-thyroid medications are continued through the morning of surgery.
TRUE
All antithyroid medications are continued through the morning of surgery. The goal of intraoperative
management is to achieve a depth of anesthesia that prevents an exaggerated sympathetic response to surgical stimulation while avoiding the
administration of medication that stimulates the sympathetic nervous system.
AVOID: Ketamine
Should the initial dose of muscle relaxant should be reduced perioperatively in patients with hyperthyroidism?
Why?
YES
The incidence of myasthenia gravis is increased
in hyperthyroid patients; thus, the initial dose of muscle relaxant should be reduced, and a twitch monitor should be used to titrate subsequent doses.
How do you treat Thyroid Storm?
Does laboratory work-up play a role?
Thyroid storm must be distinguished from, or considered with, pheochromocytoma, malignant
hyperthermia, and light anesthesia.
Although free T4 levels are often markedly elevated, NO LABORATORY test is diagnostic.
Synthesis of catecholamines:
What are the 3 Glucocorticoids that are devoid of Mineralocorticoid property?
Methyprednisolone
Triamcinolone
Dexamethasone
Which of the following glucocorticoid has the highest anti-inflammatory property?
A. Prednisone
B. Dexamethasone
C. Hydrocortisone
D. Triamcinolone
B. Dexamethasone
Which of the following glucocorticoid has the lowest anti-inflammatory property?
A. Cortisone
B. Prednisolone
C. Hydrocortisone
D. Prednisone
A. Cortisone
