Endocrine Abstracts

Overt hyperthyroidism occurs in about 0.1–0.4% of all pregnancies. Propylthiouracil (PTU) is recommended in first trimester due to risk of teratogenicity with Carbimazole (CBZ). CBZ is preferable in rest of the pregnancy and postpartum period due to risk of serious liver disease with PTU. We reviewed our management of hyperthyroidism in pregnancy from 2009 to 2014. Total number of pregnancies =34, mean maternal age 32.6 years. Except one all (33/34) were diagnosed pre- pregnancy. One diagnosed in pregnancy is likely gestational thyrotoxicosis in a twin pregnancy. Pre-pregnancy therapy was with Carbimazole (14), PTU (14), radioactive Iodine therapy (4) and surgery (1). PTU was used in first trimester in 70% (19) and 30% (8) were on CBZ. PTU was switched to Carbimazole in only 18% (3/17) in second trimester. 62% were able to come off antithyroid drug during pregnancy and this could explain low rate of conversion back to CBZ. A third of these patients relapsed in the postpartum period. TSHrAb was measured in 67% pregnancies. Growth scans were performed in 29/34 and all were normal. Mean birth weight was 3.1Kg (range 2.27–4.2 kg). There were no cases of neonatal thyrotoxicosis. Three cases of minor birth defects noted, one epispadias, one penile rotation, one skin tag below left nipple and they were exposed to PTU in first trimester. one baby had mild positional talipes. During follow up two babies were diagnosed with developmental delay, received PTU and another baby with bilateral sensorineural hearing loss was exposed to CBZ in first trimester. There are lots limitations in this small retrospective audit and in future we plan to collect data in prospective manner. We need to improve on switching more patients from PTU to CBZ in second trimester and documenting TSHrAb status as missing results could have been measured outside our hospital.