In message <2D979C08FE21D511856B00508BAE7EEA01C55EA4@NLGMAIL>, Ian
Barlow <[log in to unmask]> writes
>
> Dear colleagues,
> we have a patient with hypothyroidism who seems to be resistant
> to thyroxine replacement therapy. She is currently taking 500ug
> daily but TSH is still elevated and FT4 is still low. Poor compliance
> has been ruled out.
>
> We are speculating that she may have a de-iodinase deficiency and
> as such are considering starting her on T3. Does anyone know
> whether this could be formally investigated? There is also a strong
> family history of hypothyroidism.
>
> Many thanks for your help.
>
>
As a tertiary referral centre for thyroid problems because of Prof.
Weetman's expertise we get a number of such patients. The first step is
to rule out antibody interference in the assays, which I expect you will
have done. Coeliac disease should also be ruled out. The absorption of
thyroxine does seem to be sensitive to mucosal integrity. You say that
poor compliance has been ruled out but patients can be tricky. In our
work-up, the next step is to check the response to a large supervised
dose of thyroxine (about 1mg). The TSH should fall and the FT4 rise.
If the patient shows this pattern then they are given a weekly dose of
thyroxine which is taken supervised (1-2 mg via the district nurse or on
the ward) and the TSH followed. This eliminates a number of patients
from further investigation before other rarer causes of thyroid
dysfunction are considered.
If you want further details, then your clinician could contact Prof.
Weetman directly. You could also speak to Brian Morris in our lab. who
has the protocols used in the programmed investigation unit .
Trevor
--
Trevor Gray
Dept. of Clinical Chemistry,
Northern General Hospital,
Sheffield S5 7AU
0114 271 4309
------ACB discussion List Information--------
This is an open discussion list for the academic and clinical
community working in clinical biochemistry.
Please note, archived messages are public and can be viewed
via the internet. Views expressed are those of the individual and
they are responsible for all message content.
ACB Web Site
http://www.acb.org.uk
List Archives
http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html
List Instructions (How to leave etc.)
http://www.jiscmail.ac.uk/
|