Thyroid Disorders Flashcards
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Thyroid is a Gland that sits _________
right in the front of the neck, it is right in front of the Adams apple.
Thyroid Gland Function:
1)
2)
-
-
-
-
1) Produces Hormones & deals with them
2) Regulates Metabolism
- body temperature
- cardiac & nervous systems
- menstrual cycles
- cholesterol levels
There are 2 main disorders associated with the Thyroid:
1)
2)
1) hypothyroidism (underactive thyroid)
2) hyperthyroidism (OVERACTIVE thyroid)
The thyroid is the only gland that absorbs _________
iodine
If you are given a structure of a molecule and you see iodine, there are only a couple options, it is either _____________ or __________
thyroid hormone:
- T3 or triIODOthyronine
- T4 or thyroxine
**“iodine is required for the production of both hormones. “
OR
amiodarone
(TSH)
Thyroid Stimulating Hormone
(TSH) Thyroid Stimulating Hormone is secreted by the ___________ and goes and acts upon the ___________
Pituitary gland- which is located in the brain and regulates growth and development.
Thyroid gland stimulating it
(TRH)
Thyroid releasing hormone
(TRH) Thyroid Releasing Hormone is released by the __________ and then goes to act on the ____________
Hypothalamus
Pituitary gland
Hypothyroidism is when:
__________ is Low
&
__________ is High
free T4 is Low
&
TSH is High
Hyperthyroidism is when:
__________ is Low
&
__________ is High
TSH is Low
&
free T4 is High
In the Periphery _____________ thyroid hormone is converted to ___________
T4 ———-> T3
T4 also called ____________
thyroxine
T3 also called ____________
tri-iodothyronine
What stimulates the secretion of T4 & T3?
TSH
only about ~20% of ___________ is made by the thyroid gland
T3,
the majority of it is converted from T4 to T3 peripherally
Which thyroid hormone is more potent?
T3
Which thyroid hormone has a shorter half-life?
T3
When T3 and T4 build up in the body and there is enough in the periphery, they then communicate back to the _____________ & the ______________, shutting the system off. So we are stopping the production of TRH and TSH. So that we are not continuously producing too much thyroid hormone.
Hypothalamus
Pituitary gland
Which hormones are the thyroid hormones?
T3 & T4
Hypothyroidism = Low thyroid hormone
Low free T4 levels, and high TSH levels
Hyperthyroidism = High thyroid hormone
High free T4 levels,
Hypothyroidism, you have Low free T4 levels which communicate to the pituitary gland to increase TSH levels, since thyroid hormone levels are low since T4 is not enough. So you get high levels of TSH stimulating thyroid to make for thyroid hormone, but T4 is still low.
Hyperthyroidism, you have increased free T4 levels, more than what you need, which will communicate to the pituitary gland and shut off its production of TSH. So you will have a low level of TSH.
Hypothyroidism “underactive thyroid”
Presentation:
- Decreased metabolism
- “slowing down”/”cooling down”
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Myxedema coma: Life-Threatening Emergency
Causes
- Hashimoto’s disease (autoimmune) - destroys thyroid glans
- iodine deficiency
- drugs
- other
Signs & Symptoms
- cold intolerance
- dry skin
- fatigue
- constipation
- weight gain
- voice changes
- weakness
- depression
- menorrhagia (heavy period) - because you are not breaking down estrogen, it is building up. Which leads to a heavy menstrual cycle.
- sometimes can see a goiter
Hypothyroidism:
Diagnosis-
Monitoring-
Diagnosis-
CHECK
- free thyroid hormone (T4) - low
- thyroid stimulating hormone (TSH) - high
Monitoring-
- TSH is primarily tested for monitoring, just can’t check right away.
- TSH is Slow to respond
- Monitor every 4-6 weeks until normal, then
- 4- 6 months later, then yearly
if overtreatment = then HYPERthyroidism occur
What Keys drugs cause hypothyroidism?
** remember** I TALC
“I Take Levothyroxine To Avoid Complications”
- Interferons*
- Tyrosine Kinase inhibitors (sunitinib)
- Amiodarone*
- Lithium
- Carbamazepine
others:
phenytoin
oxcarbazepine
Myxedema coma: Life-Threatening Emergency
Is a decompensation of _______________
hypothyroidism
“the extreme end level”, is a full slowing down of all systems.
What is the main cause of Hypothyroidism in US?
Outside of US the main cause we see is?
Hashimoto’s disease
Iodine deficiency
Drug treatment for Hypothyroidism:
What is the drug of choice?
How do we dose?
Pearls/Notes
We are just giving more of what the patient is missing with hypothyroidism.
Levothyroxine (T4) is the drug of choice.
Dosing = 1.6mcg/kg/day (IBW), unless a cardiac patient for patient is elderly we would start at a low standard dose 25mcg and see how they do
Dose CONSISTENTLY:
- Take 60 minutes before breakfast (with water) not milk
- Can take at bedtime (at least 3 hours after the last meal)
- therapeutic equivalence issues, make sure to check orange book for equivalence between different brands
How many strengths are available for levothyroxine tablets?
colors universal
remember
“ Orangutans Will Vomit On You Right Before They Become Large, Proud Giants”
Orange - 25mcg
White - 50
Violet - 75
Olive - 88
Yellow - 100
Rose - 112
Brown -125
Turquoise - 137
Blue - 150
Lilac - 175
Pink - 200
Green - 300
What is the IV:PO conversion of levothyroxine?
0.75:1
Drug interactions with Levothyroxine: Anything that binds
-antacids
- multivitamins
- calcium
- hepatic inducers (amiodarone/beta blockers/protein bound drugs
Hyperthyroidism “overactive thyroid gland”
Presentation:
- Increased metabolism
- “Speeding up” “heating up” overheating
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-
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Causes:
- Graves disease (autoimmune) - antibodies stimulate the thyroid to increase T4. “antibodies mimic TSH”
- thyroid nodule
- certain drugs
- excess thyroid replacement
Signs & Symptoms:
- heat intolerance/sweating
- agitation
- palpitations/tachycardia
- light/absent menstrual periods - since breaking down estrogen very quickly
- diarrhea
- weight loss
- tremor
- thinning hair
- exophthalmos “bulging eyes”
- sometimes can see a goiter
Treatment of hyperthyroidism:
- Use to be managed with radioactive iodine (RAI-131) - historically the Tx of choice for Graves’ disease
- Thyroidectomy (partial or complete)
-Drugs:
(PTU) propylthiouracil
methimazole
beta-blockers to control symptoms
temporary effect from potassium iodide (Lugol’s solution) or saturated solution of potassium iodide (SSKI)
What drugs will decrease production of thyroid hormone when treating hyperthyroidism?
Propylthiouracil
Methimazole
Potassium Iodide Treatment:
If choosing to treat with hyperthyroidism with radioactive iodide, should be concerned since radiation can be a problem. The risk of radiation is ___________________.
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-
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thyroid cancer after being given.
- blocks accumulation of radioactive iodine in thyroid gland
- prevents thyroid cancer
- take as soon as possible after exposure
- dosing available on CDC website, which is dependent on the age of the individual and the amount of time of the exposure
What Key drugs can cause hyperthyroidism?
interferons
amiodarone
goiter:
is a growth of the thyroid gland.
Thyroid storm:
complication of _________
signs and symptoms:
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-
-
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A Life-threatening emergency
complication of hyperthyroidism, caused by some kind of stressor on the body like an infection
Signs and symptoms:
- Fever > 103 F
- Tachycardia
- Tachypnea
- Dehydration
- Profuse sweating
- Agitation
- Delirium
- Psychosis
- Coma
Drug treatment:
1) PTU plus
2) iodide (SSKI or Lugol’s) plus
3) beta-blocker plus
4) dexamethasone
- Along with supportive treatment (cooling, fluids, etc)
For Hyperthyroidism in patients who want to become pregnant
Thyroid hormone requirements can change in pregnancy.
If treatment is needed for Hyperthyroidism:
(PTU) Propylthiouracil is preferred in ______________
Historically, methimazole preferred for ____________
1st trimester
remainder of pregnancy. But can stay with PTU.
Both drugs have teratogenic risk but PTU has a lower risk in the first trimester.
Thyroid hormone requirements can change in pregnancy.
If treatment is needed for Hypothyroidism:
then the drug of choice is _____________
Levothyroxine still drug of choice
30-50% increase in dose needed
PTU
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propylthiouracil
Tapazole
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methimazole
Cytomel
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liothyronine (T3)
Thyrolar
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liotrix [T3 and T4 in a 1:4 ratio]
Triostat
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liothyronine (T3)
Armour Thyroid
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thyroid, desiccated USP (T3 and T4)
NP Thyroid
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thyroid, desiccated USP (T3 and T4)
Nature-Thyroid
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thyroid, desiccated USP (T3 and T4)
Synthroid
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levothyroxine (T4)
Levoxyl
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Tirosint
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Unithroid
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Euthyrax
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Tirosint-SOL
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