Endocrine Abstracts

Hypothyroidism (including subclinical hypothyroidism) occurs in about 2.5% of pregnancies. During pregnancy, maternal thyroid hormone requirements increase. It is known that the pregnant woman is the sole source of the fetal supply of thyroid hormones from conception to approximately 13 weeks of gestation when fetal thyroid function has developed. Organogenesis particularly of the nervous system is dependent on adequate thyroxine levels in fetal circulation. An elevated thyrotropin concentration, during pregnancy has been associated with impaired cognitive development and increased fetal mortality. Local guidelines recommend thyroid function at booking in all pregnant women with personal or family history of thyroid disease. We aimed to audit our practice.

Method: We looked at all patients attending antenatal endocrine services for period of 12 months. About 108 pregnant women (Autoimmune hypothyroidism n=83, Iatrogenic (post Graves’) n=13 and related to thyroid cancer therapy n=12) required thyroxine to normalise their TFTs.

They were first seen in clinic at mean gestation age of 15 weeks (median 14 weeks). Only 37% were seen in first trimester. Mean gestation age at TFT check was 12 weeks. In relation to pregnancy 30/108 (27.8%) had their TFT’s checked for the first time at joint clinic. Of the remaining 78 patients, mean duration between TFT check and clinic appointment was 4 weeks (range 1–12 weeks).

Majority (90%) of women had their thyroxine dosage increased at first visit at mean gestational age 14 weeks. Percentage increase in thyroxine dosage during pregnancy over baseline was mean 48% (range 12.5–200%).

Conclusion: Findings from this audit suggest the current approach is suboptimal. There is delay in referring women to our services and more worryingly important adjustments in thyroxine dosage were significantly delayed. There is urgent need to address management of maternal hypothyroidism in pregnancy through pre-pregnancy counselling and primary care – based approach.