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Pharmacy > Thyroid > Flashcards

Thyroid Flashcards

0
Q

Pituitary gland

A

Synthesize and release thyroid stimulating hormone to stimulate thyroid

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1
Q

Hypothalamus

A

Releases thyrotropin releasing hormone to stimulate the pituitary gland

TRH suppressed by dopamine, corticosteroids, somatostatin

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2
Q

Thyroid stimulating hormone

A

Causes iodine uptake for synthesis
T3/T4 release into circulation

Stimulates synthesis of iodine transporter, thyroid peroxidase, thyroglobulin

Low T4, high TSH

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3
Q

Iodine metabolism

A

Oxidize iodide by thyroid peroxidase
Able to iodinate tyrosines

Ether linkage between iodotyrosine to form T3/T4

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4
Q

Goiter

A

Can present in both iodine deficiency and iodine excess

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5
Q

T4

A

Most abundantly produced

Thyroxine

2 Tyrosine + 4 iodines

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6
Q

T3

A

Most active metabolite

Greater affinity to thyroid receptor

Triiodothyronine

Not a good indicator of hypothyroidism

Synthesized in peripheral tissues

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7
Q

Deiodinase Activity

A

Type 1: plasma membrane of liver kidney thyroid, T3 enter bloodstream

Type 2: ER of pituitary, brain cells
T3 greedy and intercellular

Type 3: inactivator, T4-RT3, T3-T2

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8
Q

Thyroid hormone actions

A

Necessary for normal growth and metabolic stability in bone & CNS

Heart beta sensitivity and inotrope

Lipolysis of adipocytes

CHO absorption, O2 consumption

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9
Q

Grave’s disease

A

TSH receptor stimulating antibodies (TSI Ab) Grave receptor Ab

Can lead to TNT to fetus

CD8+ cells mediate toxicity

Increases with increased iodine

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10
Q

Hashimoto’s disease

A

Hypothyroid

Anti thyroid peroxidase antibody
Antibody against Na-I symporter

Can’t produce thyroid hormone
Lymphocyte infiltration and WBC damage thyroid cells

Prevalent in Japanese

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11
Q

Primary hypothyroidism

A

Iodine deficiency

Autoimmune:Hashimoto’s

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12
Q

Secondary hypothyroidism

A

Hypopituitarism

TSH deficient or inactive

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13
Q

Hypothyroid signs

A

Dry skin (diminished sweating)

Edema (puffy face, hands, feet)
Weight gain
Myxedema

Pale, Yellow tinge
Sexual dysfunction
Cardio dysfunction, diastolic HTN
Dry brittle hair

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14
Q

Thyrotoxicosis signs

A 
Weight loss (increased metabolism)
Increased appetite

Tremor
Tachycardia, high cardiac output

Warm moist skin
Dermopathy

Decreased male sexual function

Bone resorption and osteoporosis

Enlarged, firm thyroid with bruit

Lid retraction, stare

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15
Q

Solitary toxic nodule

A

Mild hyperthyroid
Palpable nodule
Hot on scan

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16
Q

HCG & TSH induced thyrotoxicosis

A

hCG binds to TSH receptor

Or

TSH secreting pituitary tumor

17
Q

Diffuse (simple goiter)

A

Iodine deficiency
Compensatory hypertrophy

Goitrogens: Brussels sprouts, cabbage
PTU, MMI, lithium

18
Q

Thyroid nodules

A

90% benign
Increase with age

Hashimoto’s is benign

Malignant: papillary carcinoma

19
Q

Thyroid secretes

A

T4

Calcitonin

20
Q

Thyroglobulin

A

Provides tyrosine for T4 synthesis

Hashimoto’s and Grave’s have antibodies against thyroglobulin

21
Q

Pendrin

A

Defect results in iodination malfunction
Goiter, hypothyroidism

Exchange iodine to the colloid

To be utilized with tyrosine on thyroglobulin

22
Q

Target tissue uptake

A

MCT8 in liver, kidney, thyroid, brain for T3 uptake (X chromosome gene) defect in men

OATP for T4 uptake in tissues

23
Q

Thyroid hormone metabolism

A

Conjugation by

Glucuronidation

Sulfation

24
Q

Hyperthyroidism treatment

A

1) thioamides inhibit thyroid peroxidase and deiodinase T4 conversion to T3
Methimazole - preferred less AE
Propylthiouracil

2) cholecystographic inhibit D1, D2
Iospanoic acid

amiodarone - block T3 binding to THR
Iodine, radioioidine

Propranolol for beta symptoms

25
Q

Iodine MOA

A

Large amounts of iodine - auto regulation - inhibit TH formation
Wolff chaikoff

Small iodine - fail autoregulation - increase thyroid hormone formation
Jod-basedow

26
Q

Hypothyroidism treatment

A

Give T4 in general, body has choice to utilize it

Give T3 if you know specific T3 defect in OATP uptake

27
Q

Thyroid TSH T4 screening

A

For women > 50 years old

28
Q

TSH range

A

0.5-4.7 mIU/L

29
Q

T4 levels

A

Free T4 0.8-2.7ng/dL

30
Q

Drugs that increase T4

A

Amphetamines
Propranolol
Nadolol

31
Q

Drugs that decrease T4

A

Glucocorticoids
Lithium
Phenobarbital
Phenytoin

32
Q

If hypothyroid

A

Need to lower dose of digoxin, insulin

Avoid opioids and respiratory depression

33
Q

Levothyroxine counseling

A

AE: CHF, angina, MI, osteoporosis

Take on empty stomach
Separate from dairy Mg

34
Q

Myxedema

A

Longstanding hypothyroidism

Stupor, coma

Hypothermia 74F
Decrease Na, glucose

Give IV levothyroxine bolus 500mcg, followed by 50-100 mcg
Hydrocortisone IV
Vasopressors, fluids, warm blanket
Can give liotrix T4-T3 combo

35
Q

Hyperthyroidism treatment

A

Surgery (give thionamide, potassium iodide, propranolol before)
Give propranolol also 7 days post-op

Radioactive iodine

Antithyroid drugs: 4-8 weeks, taper monthly based on T4

36
Q

Propylthiouracil

A

Initial: 300mg divided TID PO
Maintenance: 100mg divided TID PO

AE: hepatotoxicity

Inhibits D1

37
Q

Methimazole

A

15 mild - 60 severe mg/ divided TID

Maintenance: 10mg

AE: myopathy

38
Q

Hyperthyroidism relapse

A

Give radioactive iodine

Concentrated in thyroid
Disrupt T4 synthesis ~ Wolff chaikoff

Propranolol for adrenergic symptoms

Can give potassium iodide as adjunct

39
Q

Thyroid storm

A

Fever, Tachycardia
Dyspbea, Dehydration, Coma

Maybe due to infection, T4 OD
Treat precipitating cause

Give PTU 1000mg/day divided
Potassium iodide TID 1 hour after PTU

Esmolol IV
Propranolol PO

APAP fever, cool blanket, fluids

40
Q

Euthyroid sick syndrome

A

Normal T4
Low T3
Low TSH

Impaired T4-T3 conversion

Treat underlying condition not thyroidism

41
Q

T3 levels

A

Total: 100-200 ng/dL

Pharmacy (63 decks)

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