Levothyroxine sodium

Abstract

Type-I hypersensitivity reaction: case report A 59-year-old man developed type-I hypersensitivity reaction during treatment with levothyroxine sodium for hypothyroidism and Graves’ disease. The hypersensitivity reaction was also attributed to an excipient or filler added to the levothyroxine sodium preparation. The man was diagnosed with Graves’ disease, for which he received radioactive iodine therapy. However, he was found hypothyroid post-radioactive iodine therapy, and started receiving levothyroxine sodium [levothyroxine; route not stated] 50μg daily. Four days after initiation of levothyroxine sodium, he reported feeling unwell. His TSH level was significantly high and free thyroxine level was low. He had a history of diabetes and hypertension without any history of drug allergies. Four days after levothyroxine sodium treatment, he developed abdominal distension, dyspnoea, facial oedema and swelling of distal abnormalities. The man continued receiving levothyroxine sodium but eventually stopped its administration 2 weeks prior to current presentation due to worsening of symptoms. At clinical review, his earlier symptoms were completely resolved but he was clinically hypothyroid. He also experienced constipation and gained an additional weight of 9kg. He was then switched to a different levothyroxine sodium preparation comprising different excipients. However, the similar symptoms recurred and the next day he was admitted to the emergency department. He had swelling in his fingers and a mild facial puffiness. Upon admission, his Hb was slightly low and a renal function test indicated an acute kidney injury profile with a high creatinine level. His creatine kinase level was markedly elevated, which coincided with his severe hypothyroidism with low level of free thyroxine and high level of TSH. He was then initiated on a desensitisation protocol with levothyroxine sodium, administered by two different routes along with continuous cardiac and vital sign monitoring. Both times by both routes, no delayed or immediate hypersensitivity reaction was recorded. The therapy proved successful and no signs or symptoms of allergy were noted. Since he was able to tolerate the desensitisation protocol, it was confirmed that the fillers or excipients of the levothyroxine sodium preparation attributed to the atypical type-I hypersensitivity reaction, which resolved upon cessation of levothyroxine sodium and recurred upon re-initiation. He was discharged on day 5 of the admission with an altered dose of levothyroxine sodium.