Case Presentation
A 23-year-old female with a recent diagnosis of hyperthyroidism presented to her GP with an urticarial rash localised to her neck. She was prescribed a course of cetirizine and prednisolone. Shortly after, she presented to the emergency department with a spreading urticarial rash extending to her neck, stomach, chest, back, genitals, upper and lower legs, consisting of “extensive excoriations and dermatographia, with blanching and wheals” (figures 1 & 2 ). She had given birth to her first child as recently as four months ago and the only other medication she took on a regular basis was carbimazole, which was started one month prior to her presentation.
Investigations revealed normal inflammatory markers (CRP 2 mg/L , WBC 9.3 x 109/L ) and her renal & liver function tests all remained within normal limits. No clinical findings were evident on examination of her chest and abdomen and no focal neurology was elicited. Her FT4 two weeks prior to admission was 38.4pmol/l, with a TSH of 0.01 mU/l , although her FT4 on the day of admission was normal at 10.7 pmol/l . ​She was treated with intravenous chlorphenamine in the emergency department then admitted for observation and referred to the endocrinologist.
Over the next 48 hours she had a further exacerbation of her rash which now resulted in lip swelling and she was started on intravenous hydrocortisone and oral loratadine. Her carbimazole was stopped due to concerns it may be the cause of the rash. She was reviewed the next day and an urgent dermatology opinion was sought, whilst a full autoimmune screen was sent (all negative, see table 1). Urinalysis was also negative. Thyroid peroxidase antibody (anti-TPO) levels were raised at > 1000 iU/mL.
After dermatology review the patient was started on oral chlorphenamine (at triple the normal licensed dose), topical menthol 1% cream and her steroid dose was gradually reduced. After five days of treatment her urticaria was limited to her legs and scalp, and she had symptomatically improved.