Thyroid Disorders Flashcards
DOC for Hypothyroidism in pregnancy
Levothyroxine
30-50% increase in dose needed
DOC for Hyperthyroidism in pregnancy
1st trimester: PTU
Remainder to pregnancy: Methimazole
Compare T3 vs T4
T3 is more potent than T4 and has a shorter half-life
TSH and T4 in Hypothyroidism
T4: low
TSH: high
TSH and T4 in Hyperthyroidism
T4: high
TSH: low
What drugs causes hyperthyroidism?
Interferon
Amiodarone
Iodine
MOA of methimazole
Inhibits thyroid gland synthesis of T4 by blocking the oxidation of iodine in the thyroid gland
rationale
Methimazole is used in hyperthyroidism. T4 high and TSH low. So it stops the production of T4.
JH is a 73 yoF with heart failure and a history of an MI. She is 5’ and 103 lbs. JH was diagnosed with hypothyroidism and is to begin levothyroxine therapy. What is the starting dose?
25 mcg/day
Levothyroxine dosing 1.6 mcg/kg/day use IBW
If she didn’t have CAD then her starting dose would be 75 mcg/day but in CAD pts the starting dose is 12.5-25 mcg/day
Describe the normal regulation of thyroid function
TSH stimulates thyroid secretion of thyroxine (T4) and minimally, triithyroxine (T3). T3 is made as a result to T4 converting to T3 in the periphery.
*T3 more potent than T4.
Which organ secretes TSH which then causes T4 secretion?
Pituitary gland
Methimazole is preferred over PTU because it carries a lower risk of:
Liver damage
*PTU has a boxed warning for sever liver injury. Both can cause rash and agranulocytosis (bone marrow suppression)
What is the most common cause of hyperthyroidism?
Graves’ disease
*occurs in females 30s-40s. Graves’ is an autoimmune disorder that stimulates the thyroid to produce too much T4
Generic of Unithroid
Levothyroxine
A patient is experiencing a group of symptoms together such as muscle pain, weight loss, a butterfly rash o. Face and sunburn after sun exposure. What medication is she taking?
Methimazole
*rationale: weight loss is a cause in hyperthyroidism, DOC are PTU & methimazole.
Group of symptoms is called drug-induced lupus erythrmatosus (DILE): muscle/joint pain, butterfly rash, weight loss, photosensitivity, fatigue and depression
What is the most common cause if hypothyroidism?
Hashimoto’s disease
*autoimmune condition where patient’s own antibodies attacks the thyroid gland.
A newly diagnosed patient with hyperthyroidism was given propranolol. What does propranolol do to the thyroid?
Help control symptoms of hyperthyroidism.
*beta-blockers control symptoms of tremors and tachycardia associated with hyperthyroidism
Desiccated thyroid
Contains T3 and T4.
Active ingredient of Armour Thyroid.
*Not used as 1st line
Generic for Cytomel
liothyronine
The thyroid gland is the only organ which has the ability to absorb:
Iodine
S/SX of hyperthyroidism
SX reflect an increased metabolism
Heating intolerance/sweating Weight loss Agitation Frequent Bowel Movements Tachycardia Exophthalmos (protruding eyeballs) Thinning of hair Groiter
What drug is synthetic T4?
Levothyroxine
DOC for Hypothyroidism
S/SX of hyperthyroidism
Slow metabolism Fatigue Weight gain Dry skin Constipation Depression Memory impairment Cold intolerance Heavy menses Hoarse voice Hair loss
What medication will decrease the absorption of levothyroxine if administered at the same time?
Sevelamer
*antacids (Al, Ca, Mg), bile acid sequestrants, potassium-binding resin, phosphate-binders, iron, orlistat, sucralfate
Patient takes levothyroxine 100 mcg daily at home. She is now in the hospital and provider wants to switch her to IV levothyroxine. What is the appropriate dose?
75 mcg
*IV:PO is 0.75:1
Common side effect of propylthiouracil (PTU)
GI upset (N/V)
Patient is on Levothyroxine 75 mcg daily, follow up 4/14. What changes should be made according to her labs?
3/10:
TSH 32 (0.3-3.0)
Free T4 0.3 (0.9-2.3)
hCG: negative
4/14:
TSH 4.7 (0.3-3.0)
hCG: positive
Increase her levothyroxine dose by 30-50% because she is pregnant
TSH levels should be monitored how often?
4-6 weeks until it’s within the normal range and clinical symptoms have resolved.
JS is sent to the hospital for emergent treatment. An order for PTU is written. What other medications should be initiated?
SSKI or Lugol’s solution + dexamethasone + Propranolol + APAP
*thyroid storm
