Thyroid Flashcards
thyroxine
Thyroid hormone
T4
Children need 10x more hormone/kg boy weight
Oral, IV, IM
Half life: 7 days
Oral abs: 75-90%
Converted to T3
Less expensive
100mcg=40mcg T3
triiodothyronine
thyroid hormones
T3
More active than T4
Children need 10x more hormone/kg boy weight
Oral, IV, IM
T4+T3
thyroid hormones
Children need 10x more hormone/kg boy weight
Oral, IV, IM
propylthiouracil
thioamides / thioureylenes:
Inhibit the thyroid peroxidase decreasing:
- Oxidation
- Iodination
- Coupling step (MIT+DIT)
ORAL
Course of ACtion:
- Slow due to time it takes to deplete thyroid hormone stores
Faster than MMI but less potent and shorter duration of action
Treat pregnant women first with this but can be switched at 3rd trimester
Both can be used in lactating mothers
methimazole
thioamides / thioureylenes:
Inhibit the thyroid peroxidase decreasing:
- Oxidation
- Iodination
- Coupling step (MIT+DIT)
ORAL
Course of Action
- Slow due to time it takes to deplete thyroid hormone stores
potassium iodide
Other
Inhibits release of T3 and T4 and inhibit synthesis
ORAL
Course of Action:
- Fast but effect is transient
Adverse reaction:
- Rashes
- Swollen salivary glands
Use to PREVENT uptake of radioactive iodide after nuclear accident
radioactive iodine
Other
Treat thyroid by causing radiation damage
ORAL
Adverse reaction
- Delayed hypothyroidism
- Radiation exposure
SLOW course of action
Do not use in pregnant women
propranolol
Other
Used to alleviate symptoms associated with increased CV activity
What are the actions of thyroid hormone?
Increase basal metabolic rate
Increase HR and CO
Reduce Insulin sensitivity
Stimulate protein synthesis so essential for growth and development
How are thyroid hormones transported through the blood?
Non covalently bound to TBG
What are some causes of hyperthyroidism?
Grave’s disease
- Autoantibodies to TSHR
- Low TSH, goiter
Other forms:
- Toxic nodular goiters
- Thyroid adenomas
What are the targets for treatment of hyperthroidism?
Decrease synthesis or release of thyroid hormone
Adverse reactions to PTU and MMI?
Skin rashes (most common)
Delayed hypothyroidism
Agranulocytosis (most severe)
How long is treatment on PTU or MMI
Usually requires 12-18 months
Incidence of relapse is 50% but depends on onset of treatment, severity of disease and iodide content of diet
What is hashimoto’s disease?
Primary hypothyroidism
