Myxoedema coma following commencement of anti-TNF therapy and tuberculosis prophylaxis in a patient with RA and latent tuberculosis infection

A 67-year-old man with an 8-year history of seropositive rheumatoid arthritis (RA) on conventional synthetic disease-modifying antirheumatic drug (csDMARD) and history of hypertension and bilateral total knee replacement done 2 years ago presented with active arthritis. He was advised to switch to a biological DMARD etanercept (tumour necrosis factor inhibitor (TNFi)). For this reason, screening tests for latent tuberculosis, hepatitis B and hepatitis C were performed. His chest X-ray showed a fibrotic lesion in the left upper zone and his Mantoux test was positive. He was commenced on etanercept biosimilar along with rifampicin and isoniazid for latent tuberculosis infection. Two days after the commencement of this treatment, the patient developed a loss of appetite and somnolence. His condition progressively deteriorated culminating …