Thyroid Flashcards
What are the TSH and T4 levels in hypothyroidism?
TSH high, T4 low
What are the TSH, T4 and TSI levels in hyperthyroidism?
TSH low, T4 high, TSI high
What is the main concern for using levothyroxine?
Cardiac abnormalities (tachyarrhythmias, angina, MI)
TSH goals for hypothyroidism
0.4-4 mIU/L
How to take levothyroxine?
Empty stomach
30-60min before breakfast, 4h after dinner
Space apart from calcium/iron supplements, antacid, milk by ≥2h
Target TSH in pregnancy for the different trimesters?
1st: <2.5
2nd: <3
3rd: <3.5
Causes of hypothyroidism?
- iodine deficiency
- Hashimoto disease (autoimmune)
- iatrogenic (thyroid resection / radioiodine ablative therapy for hyperthyroidism)
- drug induced (secondary)
What drugs can affect thyroid function and how?
- amiodarone: thyroiditis (hypo/hyper)
- lithium: thyroiditis (hyper), inhibit TH secretion & release (hypo)
- interferon alpha: thyroiditis (hyper > hypo)
Can thyroid issues cause psychiatric disorders?
Yes (e.g. depression)
Causes of hyperthyroidism?
- Graves disease (autoimmune, create TSI)
- adenomas
- drug induced
Treatment options for hyperthyroidism?
- surgery
- radioactive iodine ablative therapy
- PTU, carbimazole
- propranolol (symptomatic)
How does carbimazole and PTU work?
Inhibit iodination and synthesis of thyroid hormones
(PTU can block T4/T3 conversion at periphery at high doses)
Doses of PTU and carbimazole?
PTU: higher numbers
Carbimazole: lower numbers
Major concerns on using carbimazole and PTU?
Agranulocytosis (within 3m)
Hepatotoxicity (for PTU)
Which trimester should you use which hyperthyroid drug and why?
1st: PTU (carbimazole increases risk of congenital malformations)
2nd & 3rd: carbimazole (PTU increases risk of hepatotoxicity and less potent)
