Thyroid disease in pregnancy
AFP – Thyroid disease in the perinatal period
http://www.racgp.org.au/afp/2012/august/thyroid-disease-in-the-perinatal-period/
Etg therapeutic guidelines – thyroid disorders and pregnancy
Hypothyroidism Management
- Pregestational Hypothyroidism (Already Taking Thyroxine):
- Dose Adjustment: Increase the total weekly dose by 30% once pregnancy is confirmed.
- Monitoring:
- Every 4 weeks during the first trimester.
- Every 6-8 weeks thereafter.
- Target TSH Levels: Aim for TSH 0.5-2.5 mIU/L.
Hyperthyroidism Management
- Pregestational Overt Hyperthyroidism (e.g., Graves’ Disease, Toxic Nodule):
- Referral: Refer preconception or as early as possible in early pregnancy.
- Medication Advice:
- If taking anti-thyroid drugs (carbimazole or propylthiouracil), preconception advice is strongly recommended.
- Positive TRAB and/or TSI (Even if Euthyroid):
- Monitoring: T4 and/or T3 >1.5x ULN regardless of the cause.
TSH Measurement Recommendations
- Routine TSH Measurement: Not currently recommended for every pregnant patient.
- Check TSH if:
- Current or previous treatment for thyroid dysfunction (hyper or hypothyroidism, thyroid surgery, neck irradiation).
- Known positive antithyroid antibodies.
- Age ≥ 30 years.
- Symptoms of thyroid dysfunction and/or goitre.
- Conditions such as T1DM, coeliac disease, Addison’s disease, pernicious anaemia.
- Family history of thyroid disease.
- BMI > 40.
- History of miscarriage, infertility, or pre-term delivery.
- Recent use of medications like amiodarone, lithium, or intravenous contrast for CT scan.
Iodine Supplementation
- Recommended Daily Intake (RDI): 220 mcg/day, with a maximum of 500 mcg daily.
- Commercial Multivitamins: Typically contain 150-250 mcg per daily dose.
- Role of Iodine: Required for fT4 and fT3 production in the thyroid.
Isolated Hypothyroxinaemia
- Treatment Recommendation: Treatment for isolated hypothyroxinaemia (low fT4) is not currently recommended when the TSH is normal.
