Hyperthyroidism in pregnancy
Hyperthyroidism and Pregnancy
Fereidoun Azizi
Research Institute for Endocrine Sciences
Shahid Beheshti University of Medical Sciences
Tehran, I.R. Iran
12th ICED, Tehran, Iran, Nov. 14-16, 2018
Content
- Thyroid alterations
- Thyroid function tests
- Differential diagnosis
- Management of hyperthyroidism
- Medical treatment
- Preconception counseling
Recommendation 40
When a suppressed serum TSH is detected in the first trimester (TSH less than the reference range), a medical history, physical examination, and measurement of maternal serum fT4 or TT4 concentrations should be performed. Measurement of TRAb and maternal TT3 may prove helpful in clarifying the etiology of thyrotoxicosis.
Problems with FT4 in pregnancy
- High TBG concentrations result in higher FT4 values. Low albumin in serum will yield lower FT4 values.
- In pregnant women higher concentrations of TBG and NEFA and lower concentrations of albumin relative to sera of non-pregnant
- Seven commercial FT4 immunoassays in 23 euthyroid women at term:
Albumin-dependent methods showed marked negative bias with up to 50% of subnormal values
Other methods gave values above their non-pregnant reference values
Accurate Measurement of FT4
The latest development in the field of FT4 analysis is to measure free thyroid hormones in the dialysate or ultrafiltrate using online solid phase extraction - liquid chromatography/tandem mass spectrometry.
The 95% FT4 reference intervals decreased gradually with advancing gestational age: from 1.08-1.82 ng/dL in week 14 to 0.86-1.53 ng/dl in week 20
