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On Wed, 18 Jun 2003 16:56:49 +0100, Ian Barlow <[log in to unmask]> wrote: >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. > >Ian Barlow >Scunthorpe >UK > >------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/ > Ian, Probably of no help in your case, but it reminded me of a similar presentation many years ago, the cause of which in our case I'm sure is well known to readers. We had a hypothyroid patient with a similar apparent non-response to increasing doses of thyroxine replacement, reaching 450 microg/day. After several months the endocrinologist brought her along to the monthly endo meeting as an interesting case. When she sat down she nearly 'vibrated' off the chair -clearly very thyrotoxic. The endocrinologist was somewhat taken aback. As well as thyroxine, the patient was taking cholestyramine to lower her cholesterol. It turned out that for convenience she had changed from taking thyroxine at breakfast and cholestyramine at lunchtime, to taking both at breakfast. So although the T4 doses kept going up she was effectively getting little or no T4 absorption. After some months, (and just before coming to the endo meeting)she decided to again take the two medications separately at morning and lunchtime, and so suddenly was getting the full whack of 450 microg per day. Regards, Graham White ------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/