Endocrine Abstracts

Intravenous Immunoglobin (IVIG) therapy is used in recurrent miscarriage, despite its efficacy being limited to specific sub-groups such as those with underlying immune conditions. The indications, efficacy and side effect profile of IVIG when used in pregnant women are not established. We present the case of a 41-year-old pregnant woman with one previous miscarriage, who had received IVIG as part of her fertility treatment and subsequently developed profound symptoms and biochemical evidence of thyroiditis at twelve weeks’ gestation. Prior to the IVIG therapy, she was euthyroid with no family history of thyroid disorders. Her fertility team additionally prescribed prednisolone, aspirin and folic acid. Two weeks after receiving IVIG, a viable intrauterine pregnancy of six weeks gestation was confirmed. In the following weeks, she experienced tachycardia, weight loss, heat intolerance, and tremor in the absence of Graves’ defining features. Her thyroid function tests demonstrated the following: TSH <0.01mU/l, Free T3 (FT3) 11.3 pmol/l and Free T4 (FT4) 45 pmol/l. The degree of thyrotoxicosis and ratio of thyroid hormones rendered gestational thyrotoxicosis less likely. She was therefore commenced on Propylthiouracil (PTU) 100mg daily pending TSH receptor antibody (TSHrAB) results. Two weeks later, following normalisation of her FT4 values, and negative TSHrAB confirmation, PTU was discontinued. Within four weeks, she developed a low FT4 (FT4 8.4 pmol/l, TSH <0.01mU/l) and low dose levothyroxine was commenced (50mg daily). The negative TSHRAb together with the later hypothyroid phase suggested a thyroiditis, which was thought to be precipitated by the IVIG. The definitive method of confirming this: a technetium uptake scan, is contraindicated in pregnancy. The indications, efficacy and side effect profile of IVIG in pregnancy are not fully established. This case would suggest that the safety profile requires further consideration. We believe this case demonstrates the first recorded instance of IVIG-induced thyroiditis in pregnancy.