Thyroid Disorders Flashcards
What are the physiological changes that occur in a pregnant woman that affect the thyroid function?
- increased plasma expansion & GFR -> iodine deficiency
- increased thyroid binding globulin -> increased total T3 & T4
- increased thyroid blood flow -> thyromegaly
free T4 & T3 remain unchanged
What is the cause of fall of TSH & rise of fT4 in the first trimester?
high levels of HCG
What are the causes hypothyroidism?
- iodine deficiency
- Hashimiotos thyroiditis
How does hypothyroidism present?
- cold intolerance
- constipation
- weight gain
- irregular menstruation
How is hypothyroidism managed in pregnancy?
diagnosed by: increase TSH & decreased free T4
- L-thyroxine -> increase supplemental thyroid hormone by 30% in pregnancy
- TFT every trimester -> if dose is adjusted check again after 4 - 6 weeks
- GOAL: TSH < 4 mmol/l
- iodine 150 micrograms in prenatal vitamins
What are the effects of hypothyroidism in pregnancy?
- infertility
- miscarriage & fetal loss
- neurodevelopmental delay & reduced intelligence due to low T4 in first trimester -> cretinism
What are the causes of hyperthyroidism?
- Grave’s disease
- toxic adenoma
- subacute thyroiditis
- toxic multinodular goiter
How does a woman present with hyperthyroidism?
- heat intolerance
- palpitations
- weight loss despite adequate food intake
- hair loss
- sweating
- tremors
- exophthalmos
- pretibial myxedema
Is a fetus at risk if the pregnant mother has Grave’s?
TSH receptor stimulating antibodies cross the placenta
- risk of fetal Grave’s disease after 20 weeks is proportional to antibody levels
How is hyperthyroidism managed in pregnancy?
diagnosed by decreased TSH & increased fT4
1- Beta blockers -> early management & acute relapse until anti-thyroid are effective
2- propylthiouracil -> first trimester
3- methimazole -> second trimester
- subtotal thyroidectomy -> in second trimester only
What are the indications for a subtotal thyroidectomy?
- failure of medical treatment
- suspected malignancy
- tracheal compression
What are the side effects of anti-thyroid medications?
- both -> agranulocytosis, leucopenia (fever or sore throat STOP DRUG & DO CBC)
- PTU -> hepatotoxicity
- Methimazole -> esophageal or choanal atresia & aplasia cutis
What are the effects of hyperthyroidism on the fetus?
- miscarriage
- IUGR
- stillbirth
- preterm birth
- neonatal thyrotoxicosis
What are the effects of hyperthyroidism on a pregnant mother?
- pre eclampsia
- heart failure
- thyroid crises
- death
What are the causes of a thyroid storm?
- under treatment
- infection
- labour
