II. 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
III. 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
IV. 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
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Related Studies
| Concepts | Disease or Syndrome (T047) |
| SnomedCT | 156139008, 274120003 |
| English | thyroid disease in pregnancy, thyroid disease pregnancy, diseases pregnancy thyroid, Thyroid disease in pregnancy, Thyroid disease in pregnancy (disorder) |
| Spanish | enfermedad tiroidea en el embarazo (trastorno), enfermedad tiroidea en el embarazo |
Ontology: Thyroid dysfunction in pregnancy (C0747834)
| Concepts | Disease or Syndrome (T047) |
| ICD9 | 648.13 |
| English | Thyroid dysfunction, antepartum, Thyroid dysfunc-antepart, Thyroid dysfunction of mother, antepartum condition or complication, Thyroid dysfunction in pregnancy |
| Italian | Disfunzione della tiroide in gravidanza, Disfunzione della tiroide, antepartum |
| Dutch | schildklierdisfunctie, antepartum, schildklierdysfunctie tijdens de zwangerschap |
| French | Dysfonctionnement thyroïdien, antepartum, Dysfonctionnement de la thyroïde pendant la grossesse |
| German | Funktionsstoerung der Schilddruese, antepartal, Schilddruesenfunktionsstoerung waehrend der Schwangerschaft |
| Portuguese | Disfunção tiroideia anteparto, Disfunção da tiroideia durante a gravidez |
| Spanish | Disfunción tiroidea anteparto, Disfunción tiroidea en el embarazo |
| Japanese | 甲状腺機能障害、分娩前, 妊娠時甲状腺障害, ﾆﾝｼﾝｼﾞｺｳｼﾞｮｳｾﾝｼｮｳｶﾞｲ, ｺｳｼﾞｮｳｾﾝｷﾉｳｼｮｳｶﾞｲﾌﾞﾝﾍﾞﾝｾﾞﾝ, ｺｳｼﾞｮｳｾﾝｷﾉｳｼｮｳｶﾞｲﾌﾞﾝﾍﾞﾝﾏｴ |
| Czech | Dysfunkce štítné žlázy před porodem, Dysfunkce štítné žlázy v těhotenství |
| Hungarian | Pajzsmirigy működési zavara, antepartum, Pajzsmirigy működési zavar a terhesség alatt |
