Endocrine Flashcards
Who is more affected by thyroid disease?
Women 3x more
Active hormones produced by thyroid gland?
T3 and T4
Which thyroid hormone is more potent?
T3
Which is the major circulating hormone secreted by thyroid?
T4
What form is T3 and T4 mostly in?
Bound form and T4 is inactive by TBG thyroxine binding globulin
Half life of T4?
Slowly metabolized, long half life of 7 days
Half life of T3?
Greater potency and shorter half life of 1.5 days
Thyroid hormone acts directly on what 2 sites?
Cardiac myocytes (increase contractility) and vascular smooth muscle (vasodilates)
3 usual therapies for hyperthyroidism?
- Anti thyroid (methimazole or propulthiouracil (PTU))
- Iodide
- Beta blockers
How does methimazole or PTU work?
Inhibit organification and coupling steps in thyroid hormone synthesis (MIT, T3 and T4)
How long does it take methimazole and PTU to work?
6-8 weeks to achieve euthyroid status
How does iodide work?
Inhibits release of hormones; decreasing thyroid synthesis and release so reducing gland size and vascularity
When is iodide used?
Urgent uses because immediate onset but short lived
What is iodide pretreated with?
Antithyroid drugs to avoid exacerbation
How does BB propranolol work?
Decreases T4 to T3 conversion
Hyperthyroidism general anesthesia changes (2)
- Induction agent may be slower and require increased concentration of inhaled anesthetic due to increase CO
- Increased anesthetic requirements to control BP and HR
Hyperthyroidism is thought to have increased sensitivity to what?
Catecholamines (NE, Epi, ephedrine - indirect acting agent)
What is recommended to control BP for hyperthyroidism?
Direct acting non catecholamines like phenylephrine
How are hyperthyroidism pts respiratory muscles?
Weak so may need prolonged mechanical ventilation post op
Hyperthyroid pts undergoing surgery: (3)
- Euthyroid status in preop
- Elective surgery take up to 6-8 weeks
- Treat with antithyroid agents, BB, glucocorticoids
During surgery for hyperthyroidism, what is propranolol’s 2 jobs?
- Manage CV effects
2. Decrease peripheral T4 to T3 conversion
How much Propranolol should be give for hyperthyroidism during procedure?
10mg IV and titrate to HR <90
What else can you give during procedure for hyperthyroidism and why?
Dexamethasone
Decrease peripheral conversion of T4 to T3
Steps to occur to treat thyroid storm (8)
- Immediately administer BB
- Consult endocrinologist
- Propranolol 10 mg IV
- Dexamethasone 2mg IV or hydrocortisone 100-200mg
- Cooling blankets
- Acetaminophen
- Phenylephrine if vasopressor needed
- NG administration of antithyroid drug (PTU)
If symptom during or shortly after surgery in pt without known hyperthyroidism and before lab confirmation, how do you mange?
Manage like MH
Pts with chronic hypothyroidism are treated with what (3)
Thyroid replacement hormone:
- Levothyroxine (T4)
- L-triiodythyronine (T3)
- Liotirx (T4:T3 ratios)
Initiating therapy for hypothyroidism should be taken caution in pt with?
CAD
Pts with severe hypothyroidism is at higher risk for what?
Anesthetic complications
What is a term used to denote severe hypothyroidism?
Myxedema
Hypothyroidism will typically have what sign and how to treat?
Bradycardia and diminished response to adrenergic agents (alpha and beta agonists) so need larger doses
Hypothyroidism causes sensitivity to agents that cause what?
Suppress respiratory drive and that delays extubation
PONV in thyroid surgeries (3)
- At least one prophylactic agent (ondansetron class)
- Opioid sparing strategy for pain relief (acetaminophen or NSAIDs)
- TIVA if high risk pt
Extubation for thyroid surgeries (2)
- Extubate under deeper anesthesia
2. Administer remifentanil, dexmedetomidine, or lidocaine during emergence
Primary adrenal insufficiency
Addison’s disease
What is Addison’s disease?
Adrenal gland unable to provide corticosteroid, mineralocorticoid androgen hormones
Short acting glucocorticoid?
Hydrocortisone
Intermediate acting glucocorticoid (4)
- Prednisone
- Prednisolone
- Methylprednisolone
- Triamcinalone
Long acting glucocorticoid?
Dexamethasone
Which drug is most common with adrenal suppression?
Prednisone 20 mg for more than 3 weeks
8 corticosteroid adverse effects:
- Increased susceptibility to infection
- Musculoskeletal (muscle wasting, poor wound healing, osteoporosis)
- Ocular (cataracts)
- Endocrine (wt gain, cushingoid state, hyperglycemia)
- Dermatologic (acne, striae, skin atrophy, easy bruising)
- GI (peptic ulcer, bleeding)
- Nervous system (behavior change, insomnia, euphoria, psychosis, suicidal, mood change)
- Electrolyte (hypokalemia, Na retention with edema, HTN)
11 corticosteroid therapeutic uses:
- Allergic rxns
- Collagen vascular disease (RA, polymyalgia, lupus, arteritis)
- GI (IBD)
- Hematologic (immune)
- Systemic inflammation ARDS
- Inflammatory to joints and bones
- Neurologic (cerebral edema)
- Organ transplant for rejection prevention
- Pulmonary disease (COPD, asthma, sarcoidosis)
- Dermatologic disease
- Nephrotic syndrome
Acute withdrawal effects:
Occurs with abrupt discontinuation after prolonged administration of pharmacologic doses (greater than physiologic doses)
Does superficial surgery (dental, biopsy) need hydrocortisone?
No
Hydrocortisone sode for minor surgery (inguinal hernia repair)
25 mg
Hydrocortisone dose for moderate surgery (cholecystectomy, colon resection)
50-75 taper 1-2 days
Hydrocortisone dose for major surgery (CV, whipple)
100-150 taper 1-2 days
Hydrocortisone dose for ICU (sepsis, shock)
50-100 to 8hr 2-7 days
Tumor from extra adrenal chromaffin cells of the sympathetic ganglia of the thorax, abdomen, and pelvis.
Paraganglioma
Where are catecholamine secreting tumors that arise from adrenomedullary chromaffin cells mostly located?
Adrenal gland
Pheochromocytoma mostly secrete what?
NE
Pheochromocytoma rarely secrete?
Dopamine
About 15% of pheochromocytoma release what?
Only Epi
Pheochromocytoma symptoms with NE:
Alpha effects
-increased BP with reflex bradycardia
Pheochromocytoma symptoms with Epi:
Beta effects
-increase BP and tachycardia
Pheochromocytoma symptoms of BG?
Elevated due to glycogenolysis and inhibition of insulin release
Pheochromocytoma diagnosis (4)
- 24hr urine collection for measurement of metabolites (metanephrines, VMNA)
- Plasma free metanephrine concentration
- Clonidine suppression test (suppress plasma catecholamines and metabolites)
- CT and MRI for tumor location
Pheochromocytoma treatment:
Assuming predominant NE secreting so alpha blocking and then phenoxybenzamine (non competitive alpha 1 antagonist and some alpha 2 block)
Advantage and side effect of phenoxybenzamine?
Advantage of noncompetitive block: difficult of excess catecholamines to over
Side effects: orthostatic hypotension
If tachycardia, especially with phenoxybenzamine for Pheochromocytoma, what should be added?
BB
What should you NEVER do during treatment of Pheochromocytoma?
Never administer non selective BB before alpha block
What would Pheochromocytoma Epi secreting tumor treatment be:
Beat 1 selective antagonist (esmolol)
Which Pheochromocytoma treatment is useful for inoperable tumors?
Metyrosine
Mechanism of metyrosine?
Inhibits tyrosine hydroxylase
What can other treatments be for Pheochromocytoma?
CCB and ACEI
Post op management (3)
- Monitor BG (decrease catecholamines may lead to hypoglycemia)
- If bilateral adrenalectomy administer glucocorticoids -dexamethasone
- BP may continue to be high for 7-10dys bc stored catecholamines