Hypothyroidism Flashcards
what medications are used for Hypothyroidism?
Levothyroxine (synthetic form of T4)
Liothyronine (synthetic form of T3)
what are the expected blood results for hypothyroidism re: TSH and T4.
TSH high
T4 low
which hormone regulates T3 and T4?
TSH, thyroid stimulating hormone.
list the causes of hypothyroidism
1) Chronic autoimmune thyroiditis (Hashimoto’s thyroiditis)
* Typically, autoantibodies against thyroid peroxidase (TPO)
2) Iatrogenic (caused by medical examination or treatment):
* Drug-induced e.g., amiodarone, lithium, tyrosine kinase
inhibitors, valproate, etc…
* Treatment of Graves’ disease or toxic nodular disease
(primary hyperthyroidism conditions) by ablation of the
thyroid gland:
* Radioiodine treatment
* Thyroidectomy surgery
List the symptoms of hypothyroidism
● Dull facial expressions, fatigue, confusion, droopy eyelids, puffy and swollen face, sides of eyebrows fall out
● Intolerance to cold
● Excessive weight gain
● Constipation
● Muscle cramps
● Dry hair and Dry skin
● Increased or irregular menstrual flow in women
How to you administer the hypothyroidism medication?
oral route and IV
What is the difference between levothyroxine and liothyronine re: absorption?
Levo: Oral: Erratic (40% to 80% [per
manufacturer]); Decreased by
age, foods, drugs
Liothyronine: Well absorbed (95% in 4 hours)
What is the difference between levothyroxine and liothyronine re: onset?
levo: Oral: 1 to 3 days; IV: Within 6 to 8
hours
lio: Oral: 2-4 hours
What is the difference between levothyroxine and liothyronine re: half life?
levo:6-8 days
lio:1-2½ days
What is the difference between levothyroxine and liothyronine re: peak of life?
3-4 weeks
2-3 days
What is the difference between levothyroxine and liothyronine re: duration?
1-3 weeks
1-3 days
What is the difference between levothyroxine and liothyronine clinical use?
levo:
Oral for Hashimoto’s thyroiditis
IV for myxedema coma, congenital
hypothyroidism
lio: IUsed when a rapid onset of
action is needed. IV for myxedema coma.
Adverse effects of levothyroxine
In adults, overdosing can cause
cardiac arrest,
hypertension,
palpitations,
tachycardia,
anxiety,
heat intolerance,
hyperactivity,
insomnia,
irritability
and weight loss.
In children
overdosing can cause
insomnia,
restlessness,
accelerated growth
and
bone maturation.
Adverse effects of Liothyronine
Cardiac arrhythmia,
tachycardia, hypotension,
myocardial infarction.
Health education for levothyroxine and liothyronine
- Take with water only on an empty stomach in the
morning before breakfast - Wait 1 hour before taking food, soya milk, coffee,
bulk-forming laxatives (dietary fibre) - Wait 4 hours before taking iron or calcium
supplements or antacids - Bile-salt binding resins (e.g., colestyramine)
reduce absorption - Avoid soya and soya products in infants with
congenital hypothyroidism - Warn patient to keep taking consistently as it may
take 1-3 week before therapeutic benefits are felt - Serum levels of TSH monitored: High TSH levels
indicate levothyroxine dose increase is needed - Can take many months before dose is correctly
titrated as must wait 4-6 weeks for each dose
adjustment to take effect
Caution (start “low and slow”) in elderly patients and
those with pre-existing cardiac disease, hypertension,
and impaired kidney function
* Symptoms of diabetes mellitus may worsen, and
antidiabetic treatment may require dose adjustment
