Hyperthyroidism is diagnosed in pregnancy in about 0.1 - 0.4% of patients. Graves' disease is the commonest cause of thyrotoxicosis in pregnant women. The natural course of Graves' disease in pregnancy is characterised by an exacerbation of symptoms in the first trimester and during the post partum period. Symptoms usually tend to improve in the second half of pregnancy.
We describe a patient who was diagnosed with Graves' disease in the third trimester of pregnancy. A 32 year old lady was referred to the medical obstetric clinic at 30 weeks gestation with impaired glucose tolerance. There was no prior history of thyroid dysfunction and she had no symptoms of hyperthyroidism. She was noted to have moderate thyromegaly and thyroid eye disease. Graves' disease was suspected and confirmed biochemically. Serum TSH was suppressed and serum free thyroxine was elevated at 55 IU/l (ref10-23).A high titre of thyrotrophin binding inhibitory immunoglobulins (TBII) was detected.
The patient was rendered biochemically euthyroid with anti-thyroid drugs. Pregnancy proceeded uneventfully and developmental parameters of the foetus were normal. An emergency caesarean
section was performed at 41 weeks for obstetric reasons. There was no evidence of thyroid dysfunction in the neonate.
The patient remains clinically well on a block and replace regimen.
Graves' disease in pregnant women usually tends to improve or spontaneously remit in the second half of pregnancy and a decrease in thyroid stimulating antibody activity is usually observed.
Graves' disease presenting in the third trimester is uncommon. Neonatal hyperthyroidism may occur in 2-10% of infants born to women with active Grave's disease. A multi disciplinary approach is required to optimise maternal and foetal outcome.
24 - 26 Mar 2003
British Endocrine Societies