Class 3 Thyroid Flashcards
What does the thyroid gland regulate?
Metabolic rate
No thyroid gland will decrease metabolic rate by how much? Excess can raise metabolic rate by how much?
- Decrease 40-50%
- Increase 60-100%
Where is the thyroid located and how much does it weigh?
- Below the larynx, anterior and on each side of trachea
- 15-20 grams
Name the 4 hormones produced by the thyroid?
- Thyroxine (T4)
- Triiodothyronine (T3)
- Reverse T3 (rT3)
- Calcitonin
Thyroid gland is made up of what type of cells?
-Cubodial epithelial cells which surrounds a colloid matrix
What is required for thyroid hormone synthesis?
-Iodine
What two thyroid hormones are most important metabolic control?
T4, and T3
How are T4 and T3 different?
- Thyroid secretes 93% T4 compared to 7% T3
- T3 is more potent and cleared more rapidly
Explain how thyroid hormone is released?
- TRH is released by the hypothalamus
- TRH causes the release of TSH by the Pituitary
- TSH causes the release TH
What happens to T4 in the tissues?
Converted to T3
99% of TH is bound to what?
-Protein (TGB and Albumin)
TH activates what two intracellular processes?
- Gene transcription
- Protein and enzyme production
The increase in gene transcription and protein/enzyme production by TH does what?
-Increase the metabolic rate
TH increases the size and number of __________.
Mitochondria
In general the TH effect what 3 things
- Metabolism
- Growth and development
How does TH stimulate carbohydrate metabolism?
- Increase uptake of glucose
- enhances glycolsis and insulin secretion
How does TH stimulate fat metabolism?
- Mobilize lipids
- Decrease fat stores
- Decrease cholesterol
How does TH effect vitamins?
-Increase the need for vitamins
TH can decrease body weight, what can counter act that?
-TH increases appetite
How does TH effect Beta and alpha adrenergic receptors?
- Increases Beta
- Decreases Alpha
How does TH effect CV?
- Increased blood flow
- Increased CO
- Increased Heart rate
- Increased respiration
How does TH effect CNS?
- Increased mentation
- Increased Anxiety
- Increased Neurosis
Sleep effects of TH
-exhaustive / excitable effects (tired but can’t sleep)
Endocrine effects of TH
-Increases secretion, and need for hormones
Reproductive effects of TH
- Lack of TH causes loss of libido
- Excess LH causes impotence
- Inconsistent menstrual changes
What are the causes of primary hypothyroidism?
- Hashimoto’s ****
- surgical removal
- Inadequate iodine
- Radiation
- Lithium
What is primary, secondary, and tertiary hypothyroidism?
- T3 T4 are not produced (most common)
- TSH not being released from pituitary
- Inadequate TRH from hypothalamus
Hypothyroidism in infancy leads to what 2 things?
- Mental retardation
- growth deficits (cretinism)
Most severe form of hypothyroidism is called what?
-myxedema coma
High levels of TBG do what to T4
-Decrease T4
Are TSH levels high or low in primary hypothyroidism?
High, pituitary attempt to stimulate more release.
Synthroid is what? Armour Thyroid contains what?
- Synthetic T4
- T3 and T4
Problems associated with Hypothyroid and anesthesia?
- Hypotension
- Hypothermia
- Hypoventilation
- Hyponatremia
- Hypoglycemia
- Lethargy
- Bradycardia
- CHF
- Gastroparesis
Anesthetic management with hypothyroid?
- Possible crash on induction
- Ketamine used frequently
- Volatile agents not recommended
- A-Line / PA cath
- Panc/Roc have vagolytic / sympathomimetic effects
What is thyroiditis? What does it do?
- Inflammation of thyroid
- Does not produce more TH, but will release most of it stores.
Thyrotoxicosis is what?
-Over supply of TH in the tissues
What is the most common cause of hyperthyroid?
-Graves disease
How does graves disease work?
- Autoantibodies activate TSH receptor
- Causes goiter
- Stimulates TH synthesis, secretion and thyroid growth
How do beta blockers help hyperthyroidism?
- Beta blockade treats tachycardia, tremors, palpations, anxiety and heat tolerance
- D-isomer inhibits conversion of T4 to T3
How do you treat hyperthyroid?
- Antithyroid drugs (Methimazole and PTU)
- Beta blockers
- Radioactive iodine (ablates thyroid tissue)
- Surgery
S/S of thyroid storm?
- Hyperthermia
- tachycardia
- dysrythmias
- CHF
- Shock
Causes of thyroid storm
- Surgery
- Infection
- trauma
- Toxemia
- DKA
Name drugs used to treat hyperthyroid in anesthesia?
- Sodium iodide
- Cortisol
- PTU
Hyperthyroid anesthesia considerations
- Check airway (goiter)
- Treat hyperdynamism (propanolol)
- Antithyroid drugs
- Correct volume and electrolyte problems
What things should be resolved prior to elective surgery involving hyperthyroid?
- Tremor
- Heat intolerance
- nervousness
- Murmurs
- Pulse pressure
- NSR
Thyroidectomy preop concerns
- Thyroid hormone status
- Airway status
What should be done intraop for thyroidectomy?
-Neuro monitoring with nim tube or dragonfly
Post of thyroidectomy concerns
- RLN damage
- SLN Damage
- Hematoma / bleed
- Hypocalcemia
- Tracheomalacia (tracheal softening that collapse with inspiration)
RLN damage signs
- Unilateral = hoarseness
- Bilateral = aphonia, stridor, aspiration
SLN damage signs
-Abnormal voice in high pitches
What causes hyocalcemia after thyroidectomy? When? and what can happen?
- Removal of parathyroid glands
- 24-72 hours post op
- Weakness, tetany, laryngospasm, CV collapse
