Endocrine Abstracts

Section 1: Case history: A 51-year-old lady was referred to our endocrinology clinic with a 6-month history of palpitations, generalized muscle aches, heat intolerance, increased sweating and significant unintentional weight loss. She is normally fit and well without any significant past medical problem. Her thyroid function tests showed thyrotoxicosis picture with TSH < 0.05 miu/L, Free T4 76pmol/l, Free T3 > 30.8 pmol/l with positive TSH receptor antibodies ( 34.9U/L ). Her initial liver function tests were normal. The diagnosis of thyrotoxicosis secondary to Graves’ disease was made and she was started on carbimazole 40 mg once a day with propranolol 80 mg SR twice a day. 4weeks later, she developed jaundice, itchy skin, diarrhoea and dark urine.

Section 2: Investigations: Her blood results showed cholestatic picture with Bilirubin 83 umol/L, ALT102 U/L, ALP 447 U/L. Carbimazole was then stopped. She had an ultrasound abdomen which showed normal liver and biliary duct. Liver autoantibody screen and hepatitis serology for hepatitis A, B, and C were all negative. While her ALT and ALP came down within a couple of days of stopping carbimazole therapy, her bilirubin level continued to rise up to 160 umol/L on day 11 until it started to come down gradually following that.

Section 3: Results and treatment: She had a total thyroidectomy done for the definitive management of thyrotoxicosis. She developed symptomatic hypocalcemia following total thyroidectomy which was treated with one Alpha and calcium replacement therapy. Apart from that, she had a very good recovery from surgery and she was put on levothyroxine therapy for life long. On reviewing her bloods one year after thyroidectomy, she was biochemically euthyroid on levothyroxine therapy and liver function tests remained normal.

Section 4: Conclusions and Points for discussion: Cholestatic hepatitis is a rare but serious side effect of carbimazole therapy which can lead to life-threatening liver failure if left untreated. Our patient developed significant hyperbilirubinemia within 4 weeks of starting carbimazole and bilirubin continued to rise for up to 11 days after stopping the offending drug. Currently, routine monitoring of LFTs is not recommended, as cholestatic hepatitis associated with carbimazole therapy remains rare. This case highlights the importance of educating all the potential side effects to patients before starting the treatment and doing urgent investigations if patients develop adverse symptoms.