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Thyroid Disorders Flashcards

0
Q

Which is more potent? T3 or T4?

A

T3 is more potent than T4, but has a much shorter half-life

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1
Q

Role of thyroid gland?

A

One of the largest organs within the body’s endocrine system and is the only organ which contains cells that have the ability to ABSORB iodine

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2
Q

What regulates thyroid hormone production?

A

Thyroid stimulating hormone (TSH or Thyrotropin)

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3
Q

Effects of elevations of T4 levels?

A

Elevations in T4 levels => inhibits secretion of TSH and create a
negative feedback loop

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4
Q

Which is measured, T3 or T4? Why?

A

Free T4 (FT4) levels

This is the active form (T4)

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5
Q

Xtics of Hypothyroidism?

A

Deficiency of T4 => elevation in TSH

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6
Q

Xtics of Hyperthyroidism?

A

Oversecretion => low level of TSH

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7
Q

Main causes of Hypothyroidism?

A

Hashimoto’s dx - most common cause

Drugs (Amiodarone, Inteferons, Lithium, Nitroprusside, Tyrosine kinase inhibitors, Sunitinib - most notable)

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8
Q

Clinical s/sx of Hypothyroidism?

A

Cold intolerance

Dry skin

Fatigue

Weight gain

Hoarseness

Coarseness or loss of hair

Heavier than normal menstrual periods (menorrhagia)

Memory and mental impairment

Goiter

Myalgias

Weakness

Depression

Constipation

Bradycardia

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9
Q

Complications of Hypothyroidism?

A

CVD (cardiomyopathy, HF, hyperlipidemia, CAD)

Goiter

Depression

Infertility

Myxedema - intense cold intolerance, drowsiness, unconsciousness

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10
Q

Effects of hypothyroidism on body metabolism?

A

Hypothyroidism causes the body to SLOW down

T/4 u see classic sx of low metabolism - fatigue, weight gain

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11
Q

What’s the most common cause of Hypothyroidism?

A

Hashimoto’s dx

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12
Q

Diagnosis of Hypothyroidism?

A

Low free thyroxine (low FT4) - normal range 0.7-1.9 ng/dL

High thyroid stimulating hormone (high TSH) - normal range 0.3-3.0 mIU/L

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13
Q

Monitoring of hypothyroidism?

A

Check free T4 and TSH levels Q6-8 wks, until levels are normal

Then 6 months later, then yearly

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14
Q

What’s FDA pregnancy category A for hypothyroidism?

A

Levothyroxine

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15
Q

DOC in hyperthyroidism?

A

Levothyroxine (T4)

Imp to use a consistent preparation

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16
Q

What can be used to supplement Levothyroxine (T4)?

A

Liothyronine (T3, Cytomel and Triostat)

Or

Desiccated thyroid (T3 & T4, Armour Thyroid) - not usually favored

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17
Q

How should thyroid replacement therapies be used?

A

Take thyroid replacement in the morning, first thing, on an empty stomach, at least 30 mins b4 breakfast

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18
Q

Is iodine supplement used in mgt of hypothyroidism?

19
Q

List hypothyroid tx agents

A

Levothyroxine (T4) - (Synthroid, Levothroid, Levoxyl)

Thyroid Desiccated USP (T3 and T4) - (Armour Thyroid, Nature-Throid, Westhroid, NP thyroid, WP Thyroid)

Liothyronine (T3) -(Cytomel, Triostat) tablet, inj

Liotrix (T3 and T4 in 1:4 ratio) - (Thyrolar)

20
Q

Brand name of Levothroxine (T4)? Used in hypothyroid tx?

A

Synthroid

Levothroid

Levoxyl

21
Q

Are all generic Levothyroxine bioequivalent?

A

No!

Check AB-rating

22
Q

IV to PO ratio of Levothyroxine?

A

IV to PO ratio = 1:2

23
Q

Drugs that decrease thyroid hormone levels?

A

Aluminum (antacids)

Calcium

Cholestyramine

Iron

Mg

Multivitamins (containing ADEK, folate, iron)

Orlistat (Xenical, Alli)

Sevelamer

Sodium polystyrene (Kayexalate)

Sucralfate

Lanthanum

CBZ, phenobarbital, PHT, rifampin

SSRIs
Separate doses by 4 hrs

24
Effect of Thyroid hormone on anticoagulant?
Increases effect of anticoagulants (increased PT/INR with warfarin)
25
Effect of Thyroid hormone on Digoxin, Theophylline, Antidiabetic meds?
Reduce digoxin, theophylline levels and effect of antidiabetic agents
26
Xtics of Hyperthyroidism (Thyrotoxicosis)?
High FT4 and low TSH
27
Main causes of Hyperthyroidism?
Graves dx
28
Clinical s/sx of Hyperthyroidism?
Heat intolerance or increased sweating Weight loss (or gain) Agitation, nervousness, irritability, anxiety Palpitations and tachycardia Fatigue and muscle weakness Freq bowel movements or diarrhea Insomnia Light or absent menstrual periods Goiter Thinning hair Tremor Exophthalmos (exophthalmia), diplopia
29
Drugs that can cause hyperthyroidism?
Iodine Amiodarone Interferons Any pt taking excessive doses of any forms of any available forms of thyroid hormone
30
Tx of choice of for Grave's dx?
Radioactive iodine (RAI-131)
31
Role of beta-blocker in grave's dx?
Beta-blocker should be given first for sx control (to reduce palpitations, tremors and tachycardia)
32
Mao of Thionamides (used for Hyperthyroid tx)?
Inhibits synthesis of thyroid hormones by blocking the oxidation of iodine in thyroid gland PTU also inhibits peripheral conversion of T4 to T3
33
Drugs used for hyperthyroid tx?
Propylthiouracil (PTU) - (Propyl-Thyracil) Methimazole (Tapazole)
34
BBW of Propylthiouracil (PTU) - (Propyl-Thyracil) & Methimazole (Tapazole) - used for hyperthyroid tx?
Severe liver injury and Acute liver failure (with PTU)
35
SEs of Propylthiouracil (PTU) - (Propyl-Thyracil) & Methimazole (Tapazole) - used for hyperthyroid tx?
GI upset SLE-like syndrome Hepatitis Agranulocytosis (rare) - see MD at once if u develop yellow skin, abdominal pain, high fever or severe sore-throat
36
How do u use Propylthiouracil (PTU) - (Propyl-Thyracil) & Methimazole (Tapazole) - used for hyperthyroid tx - in pregnancy?
Propylthiouracil (PTU) - (Propyl-Thyracil) - preferred in 1st trimester Methimazole (Tapazole) - used in 2nd and 3rd trimesters Due to increased risk of liver toxicity from PTU
37
Hyperthyroid tx preferred in thyroid storm?
Propylthiouracil (PTU) - (Propyl-Thyracil)
38
Is PTU first-line in hyperthyroidism?
No! Except in pts who can't tolerate other options or conditions where other antithyroid therapies are CI
39
Iodides - used in hyperthyroidism?
Potassium Iodide + Iodine Solution (Lugol's solution) used off-label Saturated soln of Potassium Iodide (SSKI, ThyroShield)
40
MOA of Iodides - used in hyperthyroidism?
Temporary inhibit secretion of thyroid hormones; T4 and T3 levels will be reduced for several weeks, but effect will it be maintained
41
What's thyroid storm?
Life-threatening medical emergency caused by decompensated hyperthyroidism
42
S/sx of thyroid storm?
Fever > 103 degree F Tachycardia Tachypnea Dehydration Profuse sweating Agitation Delirium Psychosis Coma
43
Tx of thyroid storm?
PTU 900-1200mg PO - divided Q4-6 hrs + Inorganic iodide therapy such as, SSKI 3-5 drops PO Q8H or Lugol's soln 5-10 drops PO Q8H (iodine to be given 1 hr AFTER PTU) + Beta-adnerergic blockage (eg. Propranolol 40-80 mg PO Q6H) + Corticosteroid therapy (eg. Dexamethasone 2-4 mg PO Q6H) + Aggressive cooling with APAP + cooling blankets + other supportive tx (eg. Antiarrhythmics, Insulin, Fluids, Electrolytes, etc)
44
Pregnancy category of Levothyroxine (Synthroid, Levoxyl)?
A

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