28. Pharmacological Control of Thyroid and Parathyroid Flashcards
Which iodine isotope is used for diagnosis?
123I
What are the treatment options for hyperthyroidism?
Short range emission radioactive iodine
Surgery
Thioureylenes
Adjunctive therapy
What iodine isotope is used in short range emission radioactive iodine treatment?
131I
How does short range emission radioactive iodine work?
Taken up and incorporated into thyroglobulin
Emits y and B rays which kills closest cells, therefore reducing amount of thyroid hormone produced
What is the dosing of short range emission radioactive iodine?
Single dose PO
What is the half life of radioactive iodine?
8 days but can be stored for 2 months
How long does it take for radioactive iodine to work?
2 weeks
What are the side effects of radioactive iodine?
Nausea
If too much thyroid killed it can result in hypothyroidism
What are the precautions when taking radioactive iodine?
No sex for 1 month
Don’t become pregnant for 6 months
Which is more common: total or subtotal thyroidectomy?
Subtotal
Name 2 thioureylenes
Carbimazole (prodrug) converted to methimazole
Propylthiouracil
How does carbimazole work?
Inhibits thyroperoxidase which normally adds iodine to thyroglobulin to produce thyroxine
How does propylthiouracil work?
Same as carbimazole plus
inhibits 5’-deiodinase which usually converts t4 to t3
What is the half life of methimazole and how long does it take to work?
half life: 3-15 hours
90% inhibition of thyroperoxidase in first 12 hours but it can take months to see clinical results as T4 can be stored
What are the adverse effects associated with thioureylenes?
Hypersensitivity reactions: granulocytopaenia, rash, hair loss etc
What agents are given as adjunctive therapy in hyperthyroidism?
B-adrenoceptor antagonists eg. propanolol, for relief of tremor, palpitations, heat intolerance
Steroids: anti-inflammatory reduce exophthalmos
What agent is given in hypothyroidism?
Synthetic thyroxine which is converted to T3 within the body
What are the treatment options for hyperparathyroidism?
Surgery
Calcimetrics
Bisphosphonates
Calcitonin
What bone disorder is caused by:
a) hyperparathyroidism
b) hypoparathyroidism
a) osteoporosis
b) osteomalacia
Name a calcimetric
Cinacalet
How does cinacalet work?
Mimics calcium to reduce PTH release
Used in patients who are not good candidates for surgery
Name 2 bisphosphonates
Alendronate
Risedronate
What is the MOA of bisphosphonates?
Unsure but thought to inhibit osteoclasts which improve bone density
What is the MOA of calcitonin?
Inhibits calcitonin osteoclast receptor
Has some analgesic properties
Why is calcitonin not an effective drug?
PO broken down rapidly by aminopeptidases
IV is inconvenient
Nasal preparation not as effective as bisphosphonates
What adjunctive therapy is given in hyperparathyroidism?
Analgesics: patient is in constant pain from micro fractures
What are the treatment options for hypoparathyroidism?
Calcium salts
Vitamin D
Teriparatide
Why are calcium salts not given IM?
Cause necrosis
given PO
What are the side effects of calcium salts?
CKD
Kidney stones
Constipation
What are the side effects of vitamin D?
Allergic skin reactions
Build up of calcium in arteries
Change cholesterol levels
Daytime sleepiness
What route is teriparatide given?
Pen: injected IM in thigh or abdomen
What is the MOA of teriparatide?
Recombinant PTH: stimulates osteoblasts to increase bone density
What is a rare side effect of teriparatide?
Osteosarcoma
