Endocrine Abstracts

Alemtuzumab is a monoclonal antibody directed against CD52 licenced for the treatment of relapsing remitting multiple sclerosis (MS). Thyroid dysfunction occurs in one third of patients, likely secondary to lymphocyte reconstitution.

Case 1: A 36 year old female, treated with alemtuzumab 15 months prior, presented to antenatal clinic at 12 weeks gestation with symptoms of thyrotoxicosis. fT4 was 83.7 pmol/l (RR 12-22), TSH suppressed, TRAB positive. She was treated with carbimazole and remains on antithyroid medication at 30 weeks gestation; TRAB titer has risen to >40 IU/l (RR 0–1.5).

Case 2: A 36 year old male, treated with alemtuzumab 18 months prior, was admitted for investigation of weight loss and functional decline. fT4 was 37.9 pmol/l, TSH was suppressed and he had a large smooth goiter. TRAB was 18.9 IU/l. He was treated with carbimazole and is undergoing rehabilitation.

Case 3: A 39 year old female, treated with alemtuzumab 2 months prior, was referred to the endocrine clinic with fT4 of 60.2, suppressed TSH and TRAB 24 IU/l. She was asymptomatic and became hypothyroid four weeks later (fT4 <5.2 pmol/l, TSH 58 mU/l). Twelve months on, she is euthryoid on L-thyroxine 100 μg daily. In this case series we demonstrate three cases of alemtuzumab induced thyroid disease, occurring 2–18 months post treatment, all of which are TRAB positive. Case 1 highlights that women of child-bearing age treated with alemtuzumab should be counseled regarding the risk of thyroid dysfunction in future pregnancy. TRAB should be monitored in each trimester and close monitoring for foetal thyrotoxicosis is required. Case 3 highlights that TRAB positivity is not specific for Graves disease and in this case is associated with overt hypothyroidism. This case series illustrate the unpredictable clinical course of thyroid dysfunction in patients treated with alemtuzumab; long-term monitoring of thyroid function is recommended.