The best humoral marker for predictivity, already during the first trimester of gestation, is considered positivity for thyroperoxidase autoantibodies (TPOAb), though only one-third to half of such TPOAb-positive pregnant women will develop PPT.
There is evidence from observational studies and randomized controlled trials that selenium/selenoproteins can reduce thyroid peroxidase (TPO)-antibody titers, hypothyroidism, and postpartum thyroiditis.
Hypothyroid PPT patients were more often thyroid autoantibody-positive (P<0.005) and the TPO antibody median value was higher compared to hyperthyroid PPT patients (500 and 32 U/ml, P<0.0001).
Post partum thyroiditis occurs in 50% of TPO AB+ve women and is characterised by transient hyperthyroidism followed by transient hypothyroidism during the first six months, post partum.