Thyroid Disorders

Question 1

What are the physiological changes that occur in a pregnant woman that affect the thyroid function?

Answer 1

• increased plasma expansion & GFR -> iodine deficiency
• increased thyroid binding globulin -> increased total T3 & T4
• increased thyroid blood flow -> thyromegaly

free T4 & T3 remain unchanged

Question 2

What is the cause of fall of TSH & rise of fT4 in the first trimester?

Answer 2

high levels of HCG

Question 3

What are the causes hypothyroidism?

Answer 3

• iodine deficiency
• Hashimiotos thyroiditis

Question 4

How does hypothyroidism present?

Answer 4

• cold intolerance
• constipation
• weight gain
• irregular menstruation

Question 5

How is hypothyroidism managed in pregnancy?

Answer 5

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

Question 6

What are the effects of hypothyroidism in pregnancy?

Answer 6

• infertility
• miscarriage & fetal loss
• neurodevelopmental delay & reduced intelligence due to low T4 in first trimester -> cretinism

Question 7

What are the causes of hyperthyroidism?

Answer 7

• Grave’s disease
• toxic adenoma
• subacute thyroiditis
• toxic multinodular goiter

Question 8

How does a woman present with hyperthyroidism?

Answer 8

• heat intolerance
• palpitations
• weight loss despite adequate food intake
• hair loss
• sweating
• tremors
• exophthalmos
• pretibial myxedema

Question 9

Is a fetus at risk if the pregnant mother has Grave’s?

Answer 9

TSH receptor stimulating antibodies cross the placenta
- risk of fetal Grave’s disease after 20 weeks is proportional to antibody levels

Question 10

How is hyperthyroidism managed in pregnancy?

Answer 10

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

Question 11

What are the indications for a subtotal thyroidectomy?

Answer 11

• failure of medical treatment
• suspected malignancy
• tracheal compression

Question 12

What are the side effects of anti-thyroid medications?

Answer 12

• both -> agranulocytosis, leucopenia (fever or sore throat STOP DRUG & DO CBC)
• PTU -> hepatotoxicity
• Methimazole -> esophageal or choanal atresia & aplasia cutis

Question 13

What are the effects of hyperthyroidism on the fetus?

Answer 13

• miscarriage
• IUGR
• stillbirth
• preterm birth
• neonatal thyrotoxicosis

Question 14

What are the effects of hyperthyroidism on a pregnant mother?

Answer 14

• pre eclampsia
• heart failure
• thyroid crises
• death

Question 15

What are the causes of a thyroid storm?

Answer 15

• under treatment
• infection
• labour

Question 16

What is the clinical presentation of a thyroid storm?

Answer 16

hypermetabolic state that is 20 - 50% fatal
- excessive sweating
- pyrexia
- tachycardia
- atrial fibrillation
- hypertension
- hyperglycemia
- vomiting
- agitation
- cardiac failure

Question 17

How is a thyroid strom managed?

Answer 17

1- ICU admission
2- Rehydration
3- PTU in large doses
4- high dose corticosteroids
5- beta-blockers