Endocrine Abstracts

Alemtuzumab is the first humanised monoclonal antibody. It is used in haematological malignancies. It is associated with secondary autoimmune adverse effects including Grave’s disease, hypothyroidism, Goodpasture’s disease and ITP. We present a case where there was a drastic change in the thyroid biochemistry in a short span of few weeks- from raging free hormone levels to profound hypothyroidism.

A 46 year old man was found to have abnormal thyroid function tests on routine monitoring 2 years after his last Alemtuzumab infusion. He did not have any symptoms of thyroid disease. There were no signs of Grave’s disease. His previous thyroid tests had been completely normal. There was no history of thyroid or other autoimmune disease in the family.

His had positive anti-TPO and TSH Receptor antibodies. He was started on 20 mg of Carbimazole with which his thyroid chemistry improved and the drug was tapered to 5 mg.

Five weeks later, he went to his GP feeling generally unwell. At this point he had a repeat thyroid test which showed his TSH had jumped from 0.15 to 75.8, along with low free hormone levels (previously normal). He was started on 50 μg of L-thyroxine, and this had to be gradually increased.

This case offers a fascinating illustration of rapid change in thyroid function resulting from an autoimmune process. The mechanism of the thyroid dysfunction is thought to be due to lymphopenia, which results in production of self-reactive T-cells. Literature review shows a spectrum of thyroid disorders can occur-thyrotoxicosis, hypothyroidism, Grave’s disease and subclinical hyperthyroidism.

Interestingly, he did not have any symptoms despite the initial high free hormone levels. This lends weight to the recommendation of monitoring thyroid function 3 monthly following Alemtuzumab treatment and this should be done for at least 4 years since the last infusion.