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Thyroid Dysfunction in Pregnancy
Aka: Thyroid Dysfunction in Pregnancy, Thyroid Disease in Pregnancy
- See Also
- Hypothyroidism in Pregnancy
- Hypothyroidism
- Hyperthyroidism in Pregnancy
- Hyperthyroidism
- Neonatal Hypothyroidism
- Physiology: Pregnancy specific Thyroid changes
- Thyroid Hormone requirements increase by 20-40% in pregnancy (as early as 4 weeks gestation)
- Thyroid Binding Globulin increases (Estrogen mediated)
- Thyroid Hormone (Thyroxine) has a greater volume of distribution
- Placental metabolism of Thyroxine
- HCG is a weak TSH receptor stimulator in early pregnancy (decreases TSH levels), but normalizes by second trimester
- Thyroid function markers are less reliable in pregnancy
- Serum TSH normal range is lower in pregnancy (due to cross-reaction with aHCG)
- Serum T4 Free is affected by serum binding protein level changes
- Indications: Thyroid testing in pregnancy
- Many Prenatal Lab testing protocols routinely include Thyroid Stimulating Hormone (TSH)
- Current or prior Thyroid disorder management
- Hypothyroidism
- Hyperthyroidism
- Thyroid Goiter
- Postpartum Thyroid dysfunction history
- TPO Antibody Positive
- Family History of autoimmune Thyroid disease (e.g. Grave's Disease, Hashimoto's Thyroiditis)
- Type I Diabetes Mellitus
- Autoimmune disorder history
- High dose neck radiation exposure history
- Neontal Hypothyroidism with prior delivery
- Labs: Thyroid Testing
- Serum Thyroid Stimulating Hormone (TSH) normal ranges
- Non-pregnanct: 0.3 to 4.3 mIU/ml
- First trimester: 0.1 to 2.5 mIU/ml
- Second trimester: 0.2 to 3.0 mIU/ml
- Third timester: 0.3 to 3.0 mIU/ml
- Free Thyroxine (Free T4) normal ranges
- Non-pregnant: 0.8 to 1.7 ng/dl
- First trimester: 0.8 to 1.2 ng/dl
- Second trimester: 0.6 to 1.0 ng/dl
- Third timester: 0.5 to 0.8 ng/dl
- References
- Abbassi (2010) Obstet Gynecol 114(6): 1326-31 [PubMed]
- References
- Carney (2014) Am Fam Physician 89(4): 273-8 [PubMed]
- De Groot (2012) J Clin Endocrinol Metab 97(8): 2543-65 [PubMed]
- Stagnaro-Green (2011) Thyroid 21(10): 1081-125 [PubMed]