1. HypOthyroidism in pregnancy
1.1. Levothyroxine safe & effective
1.2. Will require 30-50% dose :arrow_up: & for several months after birth
2. Thyroid hormones
2.1. Triiodothyronine (T3)
2.1.1. More potent
2.2. Thyroxine (T4)
2.2.1. Shorter 1/2 life
2.3. Thyroid is only organ that can absorb iodine which is required to produce T3 & 4
3. HypOthyroidism
3.1. Drugs/Conditions causing hypOthyroidism
3.1.1. Interferons
3.1.2. Tyrosine kinase inhibitors
3.1.3. Amiodarone
3.1.3.1. Hashimoto's disease
3.1.3.2. Iodine deficiency
3.1.3.3. Pituitary failure
3.1.4. Lithium
3.1.5. Carbamazepine
3.2. Deficiency in T4 & :arrow_up: TSH
3.2.1. Depression, infertility, CV disease, slow metabolism
3.3. **Levothyroxine (T4)**
3.3.1. **Liothyronine (T3) (Cytomel)**
3.3.1.1. **Thyroid dessicated (both) (Armour)**
3.3.1.1.1. Should be taken with water 60 mins before breakfast or at bedtime @ least 3 hours after supper; same time each day
3.3.1.2. Liothyronine has shorter 1/2 life which can cause fluctuations in T3 levels
3.3.2. IV:PO is 0.75:1
3.3.2.1. Use immediately upon reconstitution
4. Drugs that :arrow_down: levothyroxine absorption
4.1. Antacids, iron, aluminum, mag, cholestyramine, sevelamer, sucralfate
4.1.1. Separate by 4 hours
4.2. Estrogen, SSRIs, & hepatic inducers :arrow_down: thyroid hormone
4.3. Levothyroxine can :arrow_up: effect of warfarin & :arrow_down: theophylline levels
5. HypERthyroidism
5.1. FT4 is high, TSH is low
5.2. Symptoms opposite of hypo
5.2.1. Weight loss, agitation, heat intolerance, insomnia, goiter, palpitations, tachy
5.2.1.1. Beta-blocker for tachy, palpitations
5.3. Most common cause is Grave's disease: antibodies stimulate thyroid to make too much T4
5.3.1. If drug-induced, likely iodine, amiodarone, & interferons
5.4. Thionamides: inhibit synthesis of thyroid hormones by blocking oxidation of iodine in thyroid gland
5.4.1. **Propylthiouracil (PTU)**
5.4.1.1. BBW: severe liver injury & acute liver failure
5.4.1.1.1. Preferred in 1st trimester pregnancy
5.4.2. **Methimazole (Tapazole)**
5.4.2.1. BBW: avoid in pregnancy
5.4.2.2. Warnings: hepatotoxicity, DILE, agranulocytosis
5.4.2.3. Usually drug of choice except in pregnancy or thyroid storm
5.4.2.3.1. 2nd & 3rd trimesters okay to :arrow_down: risk of liver toxicity from PTU
5.5. Iodides: temp inhibit secretion of thyroid hormones
5.5.1. Potassium iodide & iodide solution **(Lugol's Solution)**
5.5.1.1. Potassium iodide blocks accumulation of radioactive iodine which prevents thyroid cancer
6. Thyroid storm
6.1. **Life-threatening** medical emergency characterized by decompensated hyperthyroidism
6.1.1. Fever (> 103F), tachy, tachypnea, dehydration, profuse sweating, agitation, delirium, psychosis, coma
6.1.2. Treatment
6.1.2.1. PTU preferred
6.1.2.2. Lugol's solution
6.1.2.3. Propranolol
6.1.2.4. Dexamethasone
6.1.2.5. Cooling w/ APAP & cooling blankets