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To treat or not to treat: An interesting case of alemtuzumab-induced thyroid disorder

Shamaila Zaman, Jeannie Todd, Hammersmith Hospital, Imperial Healthcare NHS Trust.

34 year old woman with the background of multiple sclerosis and autoimmune hypothyroidism (on levothyroxine 50 mcg OD for 10 years) was given alemtuzumab infusion in July 2017. As part of surveillance, her TFTs were checked regularly. She developed thyrotoxicosis in July (TSH <0.01, FT4 84) before her next alemtuzumab infusion in August. Her GP stopped levothyroxine and she was seen in the endocrine clinic urgently. She described symptoms of palpitations, heat intolerance and weight loss for last 2-3 weeks, which were improving. On examination, her heart rate was 100/min but sweating or tremors were not noted. Neck examination did not reveal goitre or thyroid bruit. There were no features to suggest graves eye disease. Her repeat blood test showed TSH <0.01, FT3 10.1 and FT4 30. Her TPO antibodies were 148 (positive) and TSH receptor antibodies were 1.3 (positive). In view of improving biochemistry, anti-thyroid medications were not initiated. Subsequently, her ultrasound thyroid showed increased vascularity throughout normal size thyroid suggestive of thyroiditis and no nodules were identified. Her technetium scan showed reduced uptake on right suggestive of recovering thyroiditis. She was diagnosed with alemtuzumab related thyroiditis on the background of autoimmune thyroid disease. She received alemtuzumab infusion in August and her thyroid function was monitored closely, which showed gradual improvement. Her most recent thyroid function showed TSH 0.02, FT3 5.7 and FT4 14.5.

The monoclonal antibody alemtuzumab has been associated with thyroid disorder in up to 30-40% patients. (1,2) While Graves disease is the most common disorder (70%), thyroiditis has been reported up to 4.9% cases. (3) As alemtuzumab-induced thyroid disorder can present unique challenges, it is extremely important to properly investigate and closely monitor such patients.

 

References:

1.     Coles AJ, Wing M, Smith S, et alPulsed monoclonal antibody treatment and autoimmune thyroid disease in multiple sclerosisLancet1999; 354:16911695

 

2.     Pariani N, et al. Alemtuzumab-induced thyroid dysfunction exhibits distinctive clinical and immunological features. JCEM.2018; 30103018