Thyroid hormones
the amount of circulating thyroid hormone is regulated by a negative feedback loop
High levels of T3 and T4,
Suppress the function and production of TSH or TRH- thyrotropin -releasing hormone produced by the hypothalamus = inhibit their own production
Hyperthyroidism:
High t3 and t4 and low tsh
Hyperthyroidism - Signs and symptoms include:
- Increased metabolism and activity
- Hyperactivity
- insomnia
- Heat intolerance
- Increased appetite
- Weight loss
- Diarrhoea
- Goitre
Treatment - first line for hyperthyroidism
Carbimazole
Carbimazole- MHRA Guidance
- Neutropenia and agranulocytosis - report sore throat,malaise,fever
- Congenital malformations - women use contraception during treatment
- Acute pancretitis - report and stop immediately if develops signs
Propylthiouracil
patients should be cautious of liver disorder - jaundice,dark urine,nausea
Beta- blockers can be used to help with symptom relief
Graves’ disease - Radioactive iodine
Carbon and blocks of Lego
- If remission likely to be achieved with an anti- thyroids, can consider consider carbimazole
- Use carbimazole if iodine or surgery in not suitable
- Given as a block and replace regimen in combo with levothyroxine for 12-18 months
Pregnancy
- 1st trimester - propylthiouracil(due to carbimazole’s congenital defects)
- 2nd and 3rd trimester - carbimazole (due to propylthiouracil’s hepatoxicity)
Hypothyroidism:
Low T3 +T4 HIGH TSH
Hypothyroidism se
Decreased metabolism and activity
- Fatigue, weight gain,constipation,depression,dry skin,intolerance to cold,menstural irregularities
First line- hypothyroidism - HOW often do you monitor??
levothyroxine
Monitor TSH: every 3 months until stable, then yearly thereafter
Take medicine in the morning, at least 30 minutes before having breakfast or caffeinated drinks
MHRA - New guidance that a small proportion of patients can feel symptoms if alternating between brands
Liothyronine
- More rapid and potent output (20-25mcg=100mcg of levothyroxine)
- Non-uk brands may not be bio equivalent
