Hypothyroidism in pregnancy

Hypothyroidism in pregnancy

• Size :

               ♦ 10 % increase in iodine - replete areas

               ♦ 20 – 40 % increase in iodine deficient areas

• Thyroid Hormone:

               ♦ 50 % increase in T3 & T4 production

               ♦ 50 % increase in the daily iodine requirement

               ♦ Hypothyroidism in the later stages of pregnancy in iodine

                   deficient  women

• Thyroid Autoantibodies :

               ♦ 10 – 20 % of all pregnant women are TPO & Tg Ab. positive

                   in the first  trimester

               ♦ 16% will develop TSH> 4.0 mU/l  by the 3^rd trimester

               ♦ 35 – 50 % will develop post partum thyroiditis

• TSH :

               ♦ Decreases throughout pregnancy under the impact of  hCG

• SCH  : 

    ○ TSH = 2.5 – 10 mIU/L + Normal FT4

• Overt : 

   ○ TSH > 2.5 mIU/L + Low FT4

   ○ TSH > 10.0 mIU/L , irrespective of FT4

• Western  countries :

        ► OH =   0.3 – 0.5 %

        ►SCH =   2 – 3 %

• Analysis of 10 studies ( 1999 – 2007 ) from USA, Belgium , Japan , Argentina , Brazil ( Glinor et al. ) :

       ► Overall  prevalence of hypothyroidism : 2.2 – 3.4 %

            (TSH measurement : 5 – 20 weeks , TSH > 3 mIU/l to > 6 mU/l)

       ► Overall prevalence of positive thyroid Ab. = 25–77 %