Dear all,

Thyroid cases seem to be the flavour of the month so let me add another one:

- 31 year old caucasian female, 46kg but not thought to be anorectic, BMI ~21

- she appears to have selective malabsorption of Thyroxine

- Thyroxine doses of 400ug do not shift her high TSH but she becomes toxic with doses around 600ug

- her endocrinologist tells me that she appears to be compliant

- she is not on iron, PPIs or any other medication

- investigations for malabsorption have shown a negative duodenal biopsy and negative coeliac screen

- she has low folate, B12 and VitD levels but a normal full blood count: Hb 14.7, MCV 87.5.

- in her family history there is hypothyroidism on her maternal side but without any difficulties and she has a paternal aunt who used to be on i.m. Thyroxine 8 yrs ago. Unfortunately, her aunt is deceased now and no further details are available.

- the plan is to give her a trial of i.m. Thyroxine twice weekly

She could have a selective intestinal Thyroxine transporter problem. Does this really exist?

There could be an association with her low folate, Vit B12 and perhaps VitD.

I’d be grateful for your comments.

Wolf

Wolf Woltersdorf MD MRCP FRCPath

Consultant Chemical Pathologist

Head of U-STAR Research

University Hospitals Bristol

Bristol BS2 8HW UK

Tel: 0117-928 3245