Endocrine Abstracts

We would like to present this fascinating case in the forthcoming BES meeting as an oral or poster presentation.

A 65-year-old retired teacher was found on routine check up by her GP to be severely hypothyroid biochemically (TSH 70.89 mU/l (0.4–5.0) and fT4 7.5 pmol/l (12.0–23.0)).

There were no symptoms suggestive of hypothyroidism whatsoever. She was full of energy, not gaining weight, not cold intolerant, not constipated and in fact coping well with life looking after her disabled husband who has had several strokes in the past.

On examination there were no signs suggestive of hypothyroidism. Pulse was 75/min regular, BP 130/80, not overweight (BMI 22), skin was not dry, normal hair, no goitre, normal ankle reflex and no non-pitting oedema. ECG and CXR were normal.

Further investigations showed: (TFT results was checked with a reference lab).

Thyroid USS requested by GP showed normal sized thyroid with multinodular appearance but no lymph nodes or sinister features.

She was started on Thyroxin 25 μg daily but could not tolerate it. She became agitated, jittery and developed headache, palpitation and heaviness of the left arm. Different thyroxin products were tried including T3, combination of T3 and T4 and herbal thyroxin but produced the same intolerance symptoms. Even a small dose of thyroxin at 12.5 μg alternate day was not tolerated. The only product she could tolerate was Icelandic Kelp which contains iodine only.

She was referred to our Joint Endocrine Clinic with our local tertiary Hospital. The advice was to check 9:00 Am cortisol, ferritin, gastric antibodies which all came back normal. She was put on small dose of Liothyronine (T3) with B-blocker cover. The starting dose suggested was 5 mg T3 daily and then gradually increased to 5 mg tds; with the aim to swap T3 with thyroxin if the above manoeuvre succeeded.

Again she could not tolerate the above and developed the same intolerant symptoms (headache was dominant in this occassion).

Finally, we decided to put her on statin to lower the cholesterol (which might be related to hypothyroidism) and leave her alone (as she wished).

This is a very unusual case of profound biochemical hypothyroidism but euthyroid clinically and absolutely intolerant to thyroxin therapy.

We reviewed the literature and we could not find a similar case being reported. The cases which have been reported with thyroxin intolerance are either related to anaemia, iron deficiency or reaction to inactive ingredients/additives of the thyroxin tablets (causing diarrhea). All of the above are not relevant to our case.