Thyroid dysfunction during pregnancy
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Roghayeh Marandi, M.D.
Synonyms and keywords: ULRR: upper limit of the reference range
Overview
Even mild maternal thyroid hormone deficiency may lead to neurodevelopment complications in the fetus. Hence, it is important to prevent adverse maternal and fetal outcomes by timely treating thyroid disease during pregnancy. Thyroid abnormalities are not easily recognized without specific screening programs, and they are very often subclinical in nature. Serum thyroid-stimulating hormone ( TSH) and free thyroxine levels ( T4 ) are the main diagnostic indicators of thyroid disease. There are four Changes in thyroid functions that occur during pregnancy: Increase in estrogen causes increased TBG, decreased Free T4, HCG has Structural similarity with TSH and rise during pregnancy, so there is an increase in T4/ T3, decrease in TSH. Also, there is increased peripheral metabolism of thyroid hormone and a decline in iodide availability related to increased renal clearance and overall losses to the fetus and placenta.
Causes
Life Threatening Causes
Life-threatening causes include conditions that may result in death or permanent disability within 24 hours if left untreated.
- Thyroid storm due to infection, surgery, preeclampsia, and delivery
Common Causes
- Subclinical hypothyroidism
- Thyroid nodules
- Human chorionic gonadotropin-mediated hyperthyroidism
- Subclinical hypothyroidism + antithyroid peroxidase antibodies negative
- Subclinical hypothyroidism + antithyroid peroxidase antibodies positive
- Overt hypothyroidism
- Overt hyperthyroidism
- Post partum Thyroiditis
Diagnosis
Shown below is an algorithm summarizing the diagnosis of thyroid dysfunction during pregnancy according the the guidelines.
| Known Thyroid disease? | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Yes | No, Check TSH | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Hyperthyroidism | Hypothyroidism | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| TSH < 0.1 mIU/L | TSH 0.1 - 2.5 mIU/L | TSH 2.5 -10 mIU/L | TSH > 10 mIU/L | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| thyrotoxicosis | No further workup | Hypothyroidism suspected, Check TPOAb | Overt Hypothyroidism, Check TPOAb to confirm the cause is Autoimmune Hypothyroidism | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| TPOAb Positive | TPOAb Negative | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| TSH 2.5 m/UL-ULRR | TSH ULRR-10m/UL | TSH 2.5m/UL-ULRR | TSH ULRR-10mUL | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Conider treatment with Levothyroxin | Treat with Levothyroxin | No Treatment | Consider treatment with Levothyroxin | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Treatment
Shown below is an algorithm summarizing the treatment of [[disease name]] according the the [...] guidelines.
Do's
- The content in this section is in bullet points.
Don'ts
- The content in this section is in bullet points.