Endocrine Abstracts

A 76 year old woman was referred in December 1997 to the Endocrine clinic at Luton & Dunstable Hospital following admission with atrial fibrillation which was managed by digoxin, flecainide and warfarin.

Investigations initiated by her GP included reduced TSH at 0.18 milliUnits/Litre (0.32-5.00) despite normal free T4 of 14 picomols/Litre (9-24) and normal free T3 of 4.4 picomols/Litre (2.5-5.3). Ultrasound scan was in favour of multinodular goitre and thyroid isotope uptake scan was suggestive of thyrotoxicosis caused by 2 toxic thyroid nodules. Thyroid receptor antibodies checked later were >40 International Units/Litre (0 - 1.5).

Ablative radioiodine treatment was performed in February 1998 and in October 1998 following relapse of her thyrotoxicosis. She was kept on carbimazole with frequent dose titration against thyroid functions. However, there was enormous difficulty to control her thyroid status. TSH was fluctuating up to 35.22 and down to <0.06 (the patient has been very reliable and compliant with dose adjustments).

This continued till April 2003 when a detailed diet history showed that she was consuming a huge amount of vegetables of the Brassica family (sprouts, broccoli, cabbages, cauliflower).It is known that Brassica contains goitrogens that block iodine uptake .

Few weeks after stopping Brassica, her thyroid function tests normalised with carbimazole 5 milligrams daily and remained as such to date.

We report this interesting case of fluctuating thyroid functions associated with excessive Brassica intake and we recommend detailed diet history for all patients presenting with unexplained fluctuating thyroid hormone levels.