SUBCLINICAL HYPERTHYROID IN PREGNANCY

SUBCLINICAL HYPERTHYROID IN PREGNANCY

QUESTION- I have a 29 year old lady, 8 weeks pregnant, referred by her obstetrician for suppressed TSH. No family history of thyroid disorders. Asymptomatic regarding hyperthyroid symptoms.
I checked her thyroid autoantibodies ---anti TPO anti antibody, anti thyroglobulin antibody, TSH -receptor antibody --all of which are within normal reference range. FT4 and FT3 are also normal with suppressed TSH. Inflammatory markers , i.e CRP and ESR normal.
How should this person's suppressed TSH managed ? Should she be started on propylthiouracil ? Should you just wait and watch ?   Dr Sagarika Mukherjee, Consultant in  Diabetes & Endocrinology, Kolkata
RESPONSE-The TSH is often quite low (ie below the normal non pregnant reference range) during the first trimester. This is due to the presence and TSH like action of hCG which rises during the first trimester to a maximum around 12-14 weeks. Hence your patent is almost certainly normal from the thyroid point of view and does not require therapy. Even if she continues to show subclinical hyperthyroidism through pregnancy there is no evidence (from a very large study) that this is detrimental to mother or fetus.  John Lazarus, MD