Thyroid Dysfunction During Pregnancy is Overdiagnosed and Overtreated

Current practice patterns may contribute to the overdiagnosis of hypothyroidism and overtreatment during pregnancy and postpartum, reports a new study. The findings of the study are published in the journal CMAJ.

The study of more than 188 000 women in Alberta found that TSH testing was performed in more than half (111 522 or 59%) of all pregnant women who did not have thyroid disease before pregnancy. Testing was most commonly done around gestational week 5-6.

‘The practice of thyroid-stimulating hormone (TSH) testing early in the first trimester may be resulting in overdiagnosis and unnecessary thyroid hormone therapy during and after pregnancy.’

The challenge with TSH screening in pregnancy is that it identifies many women with minor TSH elevations, known as subclinical hypothyroidism. The best evidence shows no benefit for the mother or child from the treatment of pregnant women with subclinical hypothyroidism.

In 5050 (4.5%) pregnancies with TSH testing, women were started on thyroid hormone therapy; most (99%) received levothyroxine. Almost half of them (44.6%) continued with the treatment after giving birth, and almost one-third (31.5%) received two or more prescriptions in the first postpartum year.

"This raises concerns about overmedicalization during pregnancy, given that minor, untreated TSH elevation usually normalized, as indicated by repeat measurement," write the authors. "The frequent postpartum continuation of thyroid hormone therapy for those who started it during pregnancy adds to this concern."

Evidence-based clinical practice guidelines are needed to provide clinicians with the appropriate approach to deciding whether and when TSH testing is required in pregnancy and when necessary to continue treatment in the postpartum period.

Source: Eurekalert