Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharmacology > Thyroid > Flashcards

Thyroid Flashcards

1
Q

Thyroid gland

A
  • Located below the larynx
  • Synthesizes and secretes thyroid hormones: triiodothyronine (T3) and tetraiodothyronine (T4)
  • Thyroid hormones necessary for growth and development and metabolic processes, also augment SNS function (HR and PVR)
  • Thyroid: also secretes calcitonin - calcium metabolism***
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Synthesis and Release of Thyroid hormones

A

Oxidation/organification Formation of T3 and T4: thyroid peridoxase catalyzes coupling of MIT and DIT to form T3 and T4

Secretion: tsh stimulates release of t3 and t4

Conversion: t4 to t3 (t3 is more active)

Transport: to target organs by thyroid binding globulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What regulates Thyroid hormone release

A

-secretion of thyroid hormones regulated by TRH (hypothalamus) and TSH (anterior pituitary)
- thyroglobulin release stimulated by TSH
- T3 inhibits TRH and TSH secretion (negative feedback)
- production of thyroid hormone also regulated by rate of conversion of T4 to T3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Oxidation and Organification + formation of T4/T3

A

Oxidation:
- Iodide is oxidized by the enzyme thyroid peroxidase (TPO)
- TPO
- the enzyme is inhibited by PTU/meth

Organification:
- the oxidized iodine binds with tyrosine (an amino acid) to form monoiodotyrosine (MIT) and diiodotyrosine (DIT)

Formation:
- coupling: MIT + DIT catalyzed by TPO
-> T3 + T4
- typical ratio: T4:T3 (4:1)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Secretion + Transport of Thyroid hormones + regulation of release

A

secretion: TSH stimulates the proteolysis and subsequent release of T3 and T4 into the bloodstream transport:
- thyroid-binding globulin, thyroid binding prealbumin and albumin carry hormones to target organs
- T4 is converted to T3 in peripheral tissues
-> T3 is 5X MORE ACTIVE THAN T4 regulated by:
- TRH (hypothalamus) and TSH (anterior pituitary)
- negative feedback: T3 inhibits TRH and TSH release
- production of thyroid hormones is also influenced by the rate of T4 to T3 conversion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Uptake of iodide: stimulation and inhibition by what?

A

Iodide is actively transported into thyroid follicle cells
- Stimulated by TSH
- inhibited by thiocyanate and perchlorate ion ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Primary vs secondary vs tertiary thyroid disease

A

issue at:
- primary: Thyroid
- secondary: pituitary
- tertiary: hypothalamus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Hypothyroid has ____T4, ____ TSH

A

Low T4, High TSH (> 20 mlU/L)
- kids: impaired growth and development
- decrease in metabolic activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Hyperthyroid has ___T4, _____ TSH

A

High T4, Low TSH
- hyperactive organ systems
- sped up metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are some symptoms of hypothyroidism

A

weakness lethargy, cold intolerance decreased memory, hearing impairment constipation, muscle cramps, moderate, weight gain,decreased perspiration, menorrhagia depression, hoarseness, carpal tunnel syndrome dry, cool, coarse skin, dull facial expression periorbital puffiness, swelling of hands and feet bradycardia, hypothermia decreased systolic pressure increased diastolic pressure decreased body and scalp hair anemia cardiomegaly (pericardial effusion) dilutional hyponatremia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are symptoms of hyperthyroidism?

A

weakness, heat intolerance, increased appetite, weight loss, increased perspiration emotional lability, nervousness warm, moist skin exophthalmos palpitations and tachycardia increased systolic pressure,dyspnea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Hypothyroidism in children vs adults

A

Kids: irreversible mental retardation, impairs growth and development Adults: impairment of physical and mental activity, slowing of CVS, GI and neuromuscular function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

If hypothyroidism is severe can cause

A

myxedema: dry waxy non pitting edema very severe = myxedema coma
- Myxedema coma: hypothermia, hypoglycemia, weakness stupor, shock
Tx: IV levothyroxine 25-50% of PO dose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the most common cause of hypothyroidism? other causes?

A

Autoimmune thyroiditis (Hashimoto’s disease) other causes:
- Iodine deficiency
- lithium and amiodarone use

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the treatment for hypothyroidism + what do you need to be aware of

A

Levothyroxine (T4)
- Synthroid (A)
- regular adults: 100-125 mcg QD, increase by 25 mcg every 6-8 weeks until normal range
- myxedema coma: give IV dose 25-50% of oral dose*
- elderly: lower starting dose; CVD pts have even lower dose and increase every 4 wks
- DON’T CHANGE BRAND TO GENERIC!!!!!
-> differs between manufactures, keep pt on the same brand and modify dose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Levothyroxine: ADRs

A
  • Rare if dosed and monitored appropriately
  • If S/S, similar to that of Hyperthyroidism sx
17
Q

Levothyroxine: DDIs

A
  • several!!!
  • foods and drug can decrease levothyroxin absorption
    -> take on EMPTY STOMACH
  • Dependent on gastric pH so 30-60 min NPO
  • Avoid supplements for 4-6 hours
  • May increase effects of Warfarin & TCA
18
Q

Who should you start on a lower dose of levothyroxine? who will need higher doses per mg/kg?

A

start lower:
- Elderly: 50-100 mcg
- Cardiovascular disease: 12.5-25 mcg
- increase dose by 12.5-25 mcg every 4 wks Kids need higher mg/kg in terms of dosing!!!
—- regular adults: 100-125 mcg QD, increase by 25 mcg every 6-8 weeks

19
Q

What tests to monitor for hypothyroidism?

A

T4, TSH, Free T4

20
Q

What is bioavailability and half life of levothyroxine?

A

Bioavailability: 80% Half Life: 7 days
- QD dose
- converted to T3 so considered prodrug

21
Q

Other meds for hypothyroidism include

A
  • liothyronine : only T3, used in children, rarely used, need frequent dosing a day
  • liotrix: T4:T3 (4:1) fixed ratio mixture; not used
  • thyroid extracts: used to be used instead of levo
  • TRH synthetic IV
  • TSH synthetic IV
22
Q

Liothyronine

A

Hypothyroidism tx: PO: 25-50 mcg
- only T3: not used much because its rare to have just T3 deficiency
-used in children
- short half life: need multiple doses a day = bad
- does not affect T4 so cant measure response to tx

23
Q

What is the most common form of hyperthyroidism?

A

Graves Disease (toxic diffuse goiter)
- increased iodine uptake
- autoimmune disease: stimulates TSH
- Exophthalmos = characteristic

24
Q

Other causes of hyperthyroidsm?

A

Toxic nodular goiter: MC in elderly Postpartum thyrotoxicosis (painless) Thyroid storm: acute attack of hyperthyroidism

25
Q

What is thyroid storm and how do you treat?

A

Acute attack of hyperthyroidism:
- requires aggressive treatment: PTU
- Iodide slats: short term basis to tax actue thyrotoxicosis - inhibits release
- symptomatic treatment: beta blockers (tachycardia) and CCBs (HTN)

26
Q

Treatment for hyperthyroidism: Thiourea drugs

A

Propylthiouracil (PTU = pregnancy)
-unique MOA: blocks conversion of T4 to T3

methimazole** (majority) indication: give to induce remission or give before RAI/surgery to control sx prior to procedure

27
Q

MOA of thiourea drugs

A
  • blocks the peroxidase catalyzed iodination and coupling during synthesis of T3 and T4
  • essentially: inhibits TPO enzyme
  • > blocks hormone synthesis)
  • PTU: blocks the conversion of T4 to T3**
28
Q

Precautions for Thiourea Drugs

A

Avoid in SULFA allergy

29
Q

ADRs + precaution for Thiourea Drugs

A

ADRs:
-Rash **
- Hepatotoxicity **
- Agranulocytosis ** (decrease in WBCs)
- Sore throat, fever, headache
- Aplastic anemia
- thrombocytopenia

precaution: avoid in sulfa allergies

30
Q

When would thiourea drugs be used?

A

Induce remission or to control Sx prior to surgery or RAI
- GIVE FIRST LIINE before RAI and surgery until they are euthyroid/in remission and give pt choice of RAI vs surgery after
- Also used for long term remission: Tx is at least 1-2 years

31
Q

What is the treatment of choice for Grave’s Disease in pregnant patient?

A

Propylthiouracil-PTU PTU and methimazole are both cathegory D but PUT can be used in first trimester!!!

32
Q

all tx options for Hyperthyroidism

A

PTU/methimazole (thiourea drugs)
RAI
surgery
ionic inhibitors
iodide salts
sx tx: CCBs, BBs

33
Q

Ionic Inhibitors

A

Thiocyanate and perchlorate ions: BLOCK UPTAKE OF IODNIE (no iodine = no hormone production)
- cabbage
- cigarette smoke
- nitroprusside

34
Q

Iodide Salts: indication, drug names

A

Indication:
- short term basis to Tx acute thyrotoxicosis by preventing thyroid hormone release and decreasing iodine uptake
- prepare pts for surgery
- inhibit the release of thyroid hormones following RAI treatment
- pregnancy category D

Drugs: potassium iodide solutions
-SSKI (Strong solution of potassium iodide)
- Lugol’s solution

35
Q

Radioactive iodine (RAI): description, MOA, indication

A

category X!!! I 131
- t ½ is 5 days

MOA: destroys fetal thyroid tissue
- taken PO
-> rapidly absorbed into GI system
-> concentrates in thyroid gland + emits beta particles that destroy thyroid tissue
- as tissue decreases: thyroid hormone levels decrease over several weeks Indications: hyperthyroidism and thyroid cancer

36
Q

ADRs of Radioactive iodine

A
  • Hypothyroidism
  • Metallic taste
  • Nausea
  • Swollen salivary glands
37
Q

Administration instructions for radioactive iodine

A

a. Drink plenty of fluids after!!
- encourages the removal of radioactive iodine through the urine b. Sleep alone for 3 to 5 nights after treatment (dose dependent) c. Personal contact with children (hugging or kissing, for example), should be avoided for 3 to 7 days (dose dependent) First 3 days post treatment:
- stay a safe distance away from others (6 ft)
-> you’re emitting radioactive particles
- Avoid public places
- drink plenty of water
- do not share items (utensils, bedding, towels, and personal items) with anyone else
-> Do your laundry and dishwashing separately.
- Wipe the toilet seat after each use + close lid then flush
- Wash your hands often
- shower daily

38
Q

Surgery for hyperthyroidism

A

Remove all of thyroid gland and Tx patient for hypothyroidism after
- Some pts will prefer vs not prefer
- Usually will not need surgery + RAI (pts pick one vs the other)

39
Q

Symptomatic Tx for hyperthyroidism

A
  • BBs ( for tachy)
  • CCBs (for HTN)
    -same sx tx for thyroid storms

Pharmacology (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions