Anti-thyroid drugs

Question 1

What is the recommended sodium intake per day?

Answer 1

150mcg

Question 2

What transports Iodide to colloid which will be oxidized to Iodine via thryopoietin?

Answer 2

Pendrin

Question 3

What are the 2 phenomenon that induces hyper- & Hypothyroidism?

Answer 3

Wolff-Chaikoff effect -> Hypothyroidism
Jod-Basedown Phenomenon -> Hyperthyroidism

Question 4

What occurs in Wolff-Chaikoff effects & Jod-Basedown phenomenon?

Answer 4

Jod-Basedow phenomenon –> Impaired auroregulation –> escape from neg feedback –> Hyperthyroidism

Wolff-CHaikoff effect –> protective autoregulatory inhibition of organification –> protects TG –> hypothyroidism

Question 5

What is the difference betw the duration of Wolff-Chaikoff effects & Jod-Basedown phenomenon?

Answer 5

WC effect –> transient physiologic response (24-48hrs)
HB phenomenon –> pathologic response that can lead to a thyroid storm

Question 6

In what conditions do Wolff-Chaikoff effect & Jod-Basedown phenomenon occur?

Answer 6

Hashmito’s thyroiditis -> WC effect
Graves’ Disease –> JB Phenomenon

Question 7

What are the 2 types of hypothyroidism & what is its difference?

Answer 7

Primary –> problem within the TG –> Iodine deficiency
Central hypothyroidism –> problem in either PG or Hypothalamus –> TSH deficit

Question 8

What is the problem in secondary & tertiary central hypothyroidism?

Answer 8

2ndary => pituitary disease –> TSH deficit
3ary => Hypothalamic disease –> TRH deficit

Question 9

What are the diff conditions that causes primary hypothyroidism?

Answer 9

Congenital hypothyroidism => Dyshormonogenesis, Dysgenesis
Hashimoto’s thyroiditis => Autoimmune destruction of thyroid via anti-TPO
Iatrogenic hypothyroidism => After iodinated contrast media

Question 10

Which of the 2 thyroid hormones (T3 & T4) are absorbed better orally?

Answer 10

T3 = 95%

Question 11

Which of the thyroid hormones is more protein-bound?

Answer 11

T4 = 99.96%

Question 12

Which of the thyroid hormones is more potent biologically?

Answer 12

T3

Question 13

Which of the thyroid hormones has a greater total & free serum concentration?

Answer 13

T3

Question 14

What can impair T4 absorption?

Answer 14

interactions with food like brain, fiber, soy, coffee

Question 15

What is the thyroid function test result in Hypothyroidism?

Answer 15

HIGH = TSH
LOW = Total T4, Total T3, Free Te & T4

Question 16

What is the result of thyroid function test result in HYPERthyroidism?

Answer 16

HIGH = Total T3 & T4, Free T3 & T4
LOW = TSH

Question 17

Why is it that T3 is more biologically active than T4?

Answer 17

because TH receptor has a greater affinity to T3 than T4

Question 18

What are the diff effects of Thyroid hormones?

Answer 18

Growth & Development (brain & repro tissues)
Metab of CHO, Fats, CHON, vitamins, & drugs
Secretion & Degradation rates of all other hormones
INC Beta-adrenergic receptors and amplification of its signal (Palpitations, tachycardia, tremor, sweating, anxiety, heat intolerance)

Question 19

What are the clinical uses of T3 & T4?

Answer 19

Levothyroxine replacement therapy in HYPOthyroidism –> regression on nontoxic goiter if present

–> TSH suppression –> post thyroidectomy in thyroid cancer –> DEC risk of tumor recurrence

Question 20

What are the 2 preparations of T3, T4?

Answer 20

Synthetic T3 (Liothyronine)
Synthetic T4 (Levothyroxine)

Question 21

Which of the 2 preparations of Thyroid hormones is used for SHORT term TSH suppression to DEC risk of cardiotoxicity due to elevations in peak levels?

Answer 21

Synthetic T3 (Liothyronine) –> T3 + T4 combination

Question 22

Why is Synthetic T4 (Levothyroxine) the preparation of choice between the 2?

Answer 22

stability & content uniformity
lack of allergenic foreign protein
long halflife (7 days)
easy lab monitoring & low cost

Question 23

What is the basis for T4 monotherapy?

Answer 23

peripheral T4 to T3 conversion

Question 24

How much Levothyroxine is given in px?

Answer 24

50-100mcg/day
-> INC dose in pedia, preggos & thryoid cancer px
-> DEC dose in elderly & cardiac px

Question 25

What are the special instructions for administration & monitoring of Levothyroxine?

Answer 25

Take on an empty stomach 1hr before or 4 hrs after meal Measure serum TSH & FT4 before any change in dosage

Question 26

What are the possbile implications of T4 toxicity when administering Levothyroxine?

Answer 26

Pedia: restlnessness, accelerate bone growth Adult: symptoms of hyperthyroidism Elderly: A-fib & Osteoporosis

Question 27

At what point after administering Levothyroxine do you administer activated charcoal ?

Answer 27

Thyroxine toxicity

Question 28

In what case do you decrease the dose of Levothyroxine?

Answer 28

Androgen, antibiotic steroids, asparaginase administration can DEC TBG

Question 29

In what case do you INC the dose of Levothyroxine?

Answer 29

to INC metabolism of TH ,TBG (Enzyme inducers, Estrogen, Tamoxifen, Raloxifene, Methadone) & DEC peripheral conversion (Propanolol, Corticosteroids, Amiodarone)

Question 30

What are the important C/Is of Levothyroxine?

Answer 30

Uncorrected adrenal insufficiency --> adrenal crisis BBW --> DO NOT use to tx obesity/promote weight loss

Question 31

What is the end state of untreated/decompensated HYPOthyroidism associated with progressive weakness, STUPOR, hypothermia, hypoventilation, hypoglycemia, hyponetremia, H2O intoxication, shock, & Death?

Answer 31

Myxedema coma

Question 32

What should be given in px in Myxedema coma?

Answer 32

IV Levothyroxine 300-400mcg loading dose 50-100mcg daily

Question 33

What are the diff causes of HYPERthyroidism?

Answer 33

Iodine excess Amiodarone-induce thyrotoxicosis Graves disease Toxic nodular goiter (Plummer disease) Subcute thyroiditis Pregnancy Pitutary adenoma

Question 34

What condition has a goiter caused by a single toxic nodule?

Answer 34

Plummer disease/Toxic (uni- or multi-) nodular goiter

Question 35

What condition develops Ab against TSH receptors where instead of attacking/destroying them, they stimulate it?

Answer 35

Graves' disease anti-TSH-Receptor

Question 36

What condition has Amiodarone causing the disease of peripheral conversion of T4 to T3 and results in hypothyroidism? What causes this condition hyperthyroidism?

Answer 36

Amiodarone-induced thyrotoxicosis Presence of iodine in Amiodarone that can induce hyperthyroidism (~3% only)

Question 37

What is the diff betw HYPERthyroidism & Thyrotoxicosis?

Answer 37

Hyperthyroidism = INC synthesis & secretion of TH Thyrotoxicosis = Excess circulating TH

Question 38

What are important clin manifestations of HYPERthyroidism?

Answer 38

Retracted upper lids, bulging eyes, moist skin, INC HR, INC BMR, Heat intolerance, INC hormone degradation, anxiety, INC drug metabolism, DEC weight loss

Question 39

What are the 6 anti-thyroid drugs?

Answer 39

Thioamides Anions Iodides Radioactive Iodine Beta blockers w/o ISA Glucocorticoids

Question 40

What are the 2 thioamides?

Answer 40

Methimazole Propylithiouracil

Question 41

Which of the 2 thioamides is more potent, higher transfer across placenta, longer DOA?

Answer 41

Methimazole (MMI) Distribution = concentrated by Thyroid Gland

Question 42

What is the DOC betw the 2 thioamides? What is preferred during 1st trim of preggos?

Answer 42

Methimazole Preggos: Poprylthiouracil

Question 43

What is the MOA of Thioamides & Clinical use?

Answer 43

MOA: inhibits iodine organification & coupling of MIT/DIT -> PTU: inhibits peripheral deiodination of T3 &T4 Use: -> HYPERthyroidism (primary tx) -> adjunct to thyroid surgery for toxic multinodular goiter

Question 44

What are the diff Anions (anti-TD)?

Answer 44

Perchlorate, Pertechnetate, Thiocyanate

Question 45

What is the MOA, use, & Serious AE of Anions?

Answer 45

MOA: Blocks Iodide uptake through competitive inhibition of Na iodide transporter Use: Amiodarone-induced hyperthyroidism type I AE: Aplastic anemia (Disuse)

Question 46

What are the 2 Iodides (anti-TD)?

Answer 46

KI and Lugols' soln

Question 47

What is the primary tx of HYPERthyroidism/

Answer 47

Methimazole

Question 48

What are the actions of Iodides on TG?

Answer 48

DEC size Inhibits proteolysis, DEC hormone release Symptomatic, rapid relief in thyroid storm Adjuvant to thyroid surgery SHORT-TERM clinical use

Question 49

What condition can form if there is persistent Wolff-Chaikoff?

Answer 49

Fetal goiter; that's why it is avoided during preggos

Question 50

Should Iodides be administered w/ food or diluted fluids?

Answer 50

YES

Question 51

What is the MOA of radioactive iodine?

Answer 51

emission of beta rays --> destruction of Thyroid parenchyma

Question 52

What are the clinical uses of Radioactive iodine?

Answer 52

Permanent cure of thyrotoxicosis Tx of inoperable thyroid cancer Adjuvant therapy to surgery for thyroid cancer

Question 53

What are C/I of Radioactive iodine & important AEs?

Answer 53

C/I: Preggos & lactation AE: permanent hypothyroidism

Question 54

What is the MOA of beta-blockers w/o ISA?

Answer 54

competitively blocks beta-adrenergic receptors, ameliorating clinical signs and sympotoms of thyrotoxicosis & thyroid storm Atenolol, Metroprolol, Propranolol

Question 55

Which BB inhibits peripheral conversion of T4 to T3 & REDUCES T3?

Answer 55

Propranolol @ >160mg/day

Question 56

What are the uses of BB in thyroid diseases , AE, & C/I?

Answer 56

Use: Control tachycardia, HTN, A-Fib AE: Bronchospasm, bradycardia, hypotension C/I: Bronchial asthma, Severe HF

Question 57

What anti-inflam agent is used in severe hyperthyroidism?

Answer 57

Glucocorticoids

Question 58

What conditions uses Glucocorticoids during severe HYPERthyroidism?

Answer 58

to manage thyroiditis in Amiodarone or infection Relieves Sx of Graves ophthalmopathy Manages severe metabolic stress in neonatal Graves' disease

Question 59

What conditions thyroid diseases use Oral Prednisone?

Answer 59

AIT type II Severe subacute thyroiditis Severe Graves' disease

Question 60

What thyroid disease uses Topical Triamclinolone covered w/ occlusive dressing? !!!!!

Answer 60

Graves' dermopathy

Question 61

What thyroid disease uses IV Hydrocorticosterone to protect the px against shock & reduce circulating TH levels by peripheral inhibition? !!!

Answer 61

Thyroid storm

Question 62

What are diff special problems in special populations?

Answer 62

Graves' ophthalmopathy Thyroid storm Neonatal Graves' disease

Question 63

What drug is given in CVS symptoms of Thyrotoxicosis?

Answer 63

Propranolol

Question 64

What is the prevention of progression of Graves' ophthalmopathy?

Answer 64

Smoking cessation

Question 65

What DOC is given to Graves' opthalmopathy?

Answer 65

Oral Prednisone Alt: irradiation of posterior orbit

Question 66

What are tx of underlying thyroid dis & management of complications?

Answer 66

Tx of underlying thyroid dis: Surgery or RAI Management of complications: -> threatened visual loss: SURGICAL DECOMPRESSION OF ORBUT -> residual eyelid/eye muscle problems: SURGERY

Question 67

What drugs are used in cases of thyroid storm?

Answer 67

Propanolol Propylthiouracil Hydrocortisone

Question 68

What is the cause of neonatal graves' dis?

Answer 68

Passage of maternal TSH-R Ab through placenta into fetus

Question 69

What are the drug measures for neonatal Graves' dis?

Answer 69

PROPYLthiouracil Propanolol K Iodide (Lugol's soln) Prednisone

Question 70

What is given in 1st, 2nd, & 3rd trimester of preggo mothers w/ HYPERTHYROIDISM

Answer 70

1st trim = Polythiouracil 2nd & 3rd trim = Methimazole

Question 71

What is given in preggos mothers with HYPOTHYROIDISM?

Answer 71

Levothyroxine

Question 72

What is a definitive therapy given in subtotal thyroidectomy in 2nd trimester?

Answer 72

Methimazole