thyroid Flashcards
THYROID DISORDER: HYPERTHYROIDISM (THYROTOXICOSIS - Primary:
Hyperactivity of thyroid gland → increased levels of circulating thyroid hormone
Prevalence: about 1.2% in the US of which 0.7% is subclinical
Classified as either:
Primary: Hypersecretion of TH related to the thyroid gland
HYPERTHYROIDISM: GRAVE’S DISEASE (graves is a glob)
An autoimmune disease that results in development of antibodies to the TSH receptor
Thyroid stimulating immunoglobulins bind to TSH receptors on the thyroid gland → excess secretion of TH
Accounts for 75% of hyperthyroidism cases
HYPERTHYROIDISM: GRAVE’S DISEASE - Signs & Symptoms (grave’s goiter)
Signs & Symptoms (Lewis table 49-9):
Diffuse thyroid enlargement: goiter
HYPERTHYROIDISM: Diagnosis based on
Medical hx, physical exam, symptoms
HYPERTHYROIDISM: Treatment- Propylthiouracil (Judy is a pro)
Treatment:
Drug therapy
Propylthiouracil (PTU) 1st drug of choice: taken TID
Inhibits thyroxine synthesis and blocks conversion of T4 to T3
HYPERTHYROIDISM: Total or Partial Thyroidectomy - POST-OP CARE - lying in what position?
POST-OP CARE
Pillows to support the head, semi-fowler’s for respiratory support
Avoid hyper-flexion of neck
hYPOTHYROIDISM: PATHOPHYSIOLOGY - most common cause in US (hashi is slow)
Deficiency of thyroid hormone leading to slowing of metabolic rate
Most common cause worldwide is iodine deficiency
Uncommon in the US where iodine is usually adequate
Most common cause in US is atrophy of the thyroid gland (e.g. Hashimoto’s thyroiditis)
HYPOTHYROIDISM - HASHIMOTO’S THYROIDITIS (Chronic autoimmune thyroiditis) (Hashi is low TSH)
The most common cause of hypothyroid goiter in the US
A chronic autoimmune disease in which thyroid tissue is replaced by lymphocyte and fibrous tissue
T3 and T4 are initially elevated in subacute, acute, and silent thyroiditis but becomes depressed over time
TSH is low then elevated (feedback mechanism)
Positive anti-thyroid antibodies
HYPOTHYROIDISM-MYXEDEMA - is it lifethreatening?
MYXEDEMA (Severe and longstanding hypothyroidism)
Carries a mortality risk as high as 40 %
PARATHYROID GLANDS: HYPERPARATHYROIDISM
Over secretion of PTH
PTH regulates calcium and phosphate levels
HYPERPARATHYROIDISM: EVALUATION AND TREATMENT- Ca and phos levels (big parrot drinks too much milk at 10, and not enough phos at 3)
Diagnostic criteria:
Detection usually through routine lab work
Serum Ca >10mg/dL
Serum Phos <3mg/dL
HYPOPARATHYROIDISM- how does it happen? (little parrot got removed)
Inadequate circulating PTH
Uncommon condition
Etiology:
Commonly iatrogenic: accidental removal of parathyroid gland during neck surgery
HYPOPARATHYROIDISM: Signs and Symptoms
Signs and Symptoms related to low serum Ca+:
Hypocalcemia lowers the threshold for nerve and muscle excitation
what meds for hypoparathyroidism? (think low calcium)
For tetany, slow IV Ca gluconate so as not to cause hypotension or cardia dysrhythmias. Avoid IV CaCl unless in emergency (caustic to veins)
Oral Ca supplement with meals (gastric acid promotes Ca absorption)
Vit D is given rather than PTH
Calcitriol
PTH replacement expensive and given IV only
hyperthyroidism - Secondary
Secondary : rare; related to TSH secreting pituitary adenomas
All forms of thyrotoxicosis
share the same clinical manifestations
hyperthyroidism - disease ex. (hyper in the grave)
e.g. Graves disease, toxic multinodular goiter and rarely follicular thyroid carcinomas
complication of hyperthyroidism
Complication: Thyroid storm/Acute thyrotoxicosis manifested by infection, trauma or surgery, is a medical emergency but rarely causes death if treated early
thyroid storm - symptoms (hot storm in the hall)
Sx: restlessness, severe tachycardia, heart failure, shock, hyperthermia, delirium, seizures
thyroid storm may progress to (storms go low)
destruction of thyroid tissue → hypothyroidism
graves disease - Goiter is a result of (goiter can go either way)
Goiter is a result of hypo or hyperthyroidism, nontoxic or nodular goiter
graves - most common cause- and what foods? (salty grave)
Most common cause d/t low iodine intake or Goitrogen related
*goitrogens are foods/drugs that inhibit uptake of iodine in thyroid gland e.g. PTU, methimazole, broccoli, brussels sprouts, etc. see Lewis T49-4
graves - symptoms (you know this- just one)
Exophthalmos (bulging eyeballs) d/t impaired venous drainage from the orbitwill be on exam, increased fat deposits and fluid in the tissue behind the orbits
Weight loss, palpitations, tremors, HTN
graves symptoms - Derm related (grave legs)
Derm related: Peritibial myxedema (indurated and erythematous skin in the anterior portion of the leg)
hyperthyroidism - blood tests
Blood tests to measure thyroxine and TSH levels
Primary hyperthyroidism - how to tell - what hormone will be low?
Primary hyperthyroidism : ↓TSH (pituitary) , ↑ thyroxine (thyroid) = hyperactive thyroid (pituitary will probably be fine)
Secondary hyperthyroidism - how to tell (the second you get high, you get high)
Secondary hyperthyroidism: ↑TSH, ↑ thyroxine = pituitary over secretion of TSH
hyperthyroidism - Radioactive iodine uptake
Radioactive iodine uptake: RAIU to establish the etiology
Normal uptake is 15 to 25%
↑ uptake indicates increased thyroxine production either d/t Grave’s disease (35-95%) or presence of a thyroid nodule (normal to high uptake)
↓uptake could suggest thyroiditis (<2%)
hyperthyroidism - meds - Methimazole (meth for judy)
Methimazole inhibits thyroxine synthesis
β blockers for thyrotoxicosis (propranolol and atenolol)
hyperthyroidism - Radioactive iodine
Radioactive iodine - destroys thyroid tissue - not for pregnant woman
hyperthyroidism - Thyroidectomy
Thyroidectomy - for large goiters causing compression to trachea - no response to anti-thyroid drugs
- thyroid CA
***Complication of above treatments may lead to hypothyroidism
thyroidectomy - Watch for S & S of
Watch for S & S of hypocalcemia (can accidentally take out parathyroid glands during surgery) which is 2/2 to hypoparathyroidism. Tingling around the mouth, toes, fingers and muscle twitching. Have Ca gluconate available
thyroidectomy - Assess for laryngeal damage:
Assess for laryngeal damage: hoarseness and a weak voice are temporary
thyroidectomy - Assess for signs of tracheal compression and hemorrhage how often?
Assess for signs of tracheal compression and hemorrhage q 2hrs x 24hrs and watch for laryngeal stridor; have tracheostomy tray at bedside
thyroidectomy - measure what?
Measure neck circumference (to make sure there is no bleeding) - its called wet neck protocol - using a skin pen to mark
*Total thyroidectomy requires life-long hormone therapy (Levothyroxine)
hypothyroidism - Other causes:
post thyroidectomy or drugs to treat hyperthyroidism
Classification
hypothyroidism - Primary (primarily destroy the thyroid)
destruction of thyroid tissue or defective hormone synthesis
hypothyroidism - Secondary
related to pituitary or hypothalamic disease
primary hypothyroidism - TSH levels (again, primarily opposite)
TSH level ↑, Thyroxine ↓
secondary hypothryoidism - TSH levels (secondary makes sense)
↓ TRH and/or TSH ↓, ↓ Thyroxinem
myxedema - is it an emergency?
A medical emergency
myxedema - S/SX (mix it low)
diminished LOC, hypothermia, hypotension, hypoventilation, lactic acidosis
myxedema - causes (myxa the drugs)
Precipitated by: Infection, narcotics, sedatives, cold and trauma
myxedema - treatment (just thyroid hormones)
Treatment: IV thyroid hormone in addition to regular resuscitation of IV fluids, IV corticosteroids, warming blanket, pressors
myxedema - Clinical manifestations (mix the mask down low)
Clinical manifestations:
Mental sluggishness, masklike appearance, skin dull and puffy and periorbital edema (d/t hydrophilic mucopolysaccharides) usually depression
Myxedema coma
hyperparathyroidism- PTH In the bone (the parrot stimulates)
In the bone, stimulates Ca and Phos bone resorption
PTH - In kidneys
In kidneys increases renal tubular reabsorption of calcium and increase phosphate excretion
PTH - In the GI - but how?
In the GI, activation of Vit D to increase Ca and Phos
absorption
**Net result is increase Ca level and slight decrease
in phosphate levels
hyperparathyroidism - labs (think bones, kidneys, inestines tests)
Other labs: Elevation in urine Ca, uric acid, serum Cl, creatine, amylase
Bone density test to detect bone loss
hyperparathyroidism = Treatments (just surgery)
Treatments:
Partial or complete parathyroidectomy most effective for primary and secondary hyperparathyroidism
hyperparathyroidism = treatment (think, too much Ca - get it out)
Symptom management with: routine monitoring of labs, IV NS and loop diuretic to ↑urinary excretion of Ca, Bisphosphates (Alendronate) inhibits bone resorption, Sensipar for secondary hyperparathyroidism to ↑sensitivity of Ca receptors on the parathyroid gland → less bone loss
hypoparathyroidism - complications - magnesium
Severe hypomagnesemia r/t alcoholism and malabsorption. Low Mg suppresses PTH secretion
hypoparathyroidism - Diagnosis
Diagnosis:
↓ Ca and ↑ Phos in the absence of renal failure, intestinal disorders or nutritional deficits
hypoparathyroidism - symptoms
Tingling of the lips, fingertips and feet
Muscle spasm and tetany
Hyperreflexia
Tonic-clonic convulsions
hypoparathyroidism - tests (chvosteks)
Positive Chvostek’s
Tapping the facial nerve about 2 cm anterior the tragus of the ear results in twitching at the angle of the mouth, followed by nose, eye and facial muscles
Trousseau signs
Carpal spasm is noted on inflation of a BP cuff above systolic pressure
Laryngeal spasms and in severe cases and death from asphyxiation
hypoparathyroidism - foods high in Ca
Teach pt about foods high in Ca: dark green vegetables, soy beans and tofu
Avoid foods high in oxalic acid which inhibit Ca absorption: spinach, rhubarb, etc.
myxedema - hypo or hyperthyroidism?
(mix it down low)
hypo
