A primary cause of reduced conversion of T4 to T3 is extremely rare. Likewise receptor defects that alter the uptake of thyroid hormone into the cell are extremely rare. In contrast intercurrent illness of a non-thyroidal nature can bring about subtle effects on thyroid hormone metabolism. The best ...

When I started measuring thyroid hormones in my laboratory 35 years ago I established an assay for reverse T3 (rT3). Several other laboratories did the same. The assay helped us a little in understanding the cause and time course of non-thyroidal illness but as experience of the assay grew there was...

It is not possible to answer the question 'what is an ideal TSH?' The best advice available in thyroid hormone replacement therapy is to reduce or alleviate symptoms whilst maintaining the serum TSH within the reference range (broadly 0.5-4.5mU/L). In most patients this can be achieved. However, in ...

Mirielle, I will reply but I suspect that I may not be able to answer your query to your satisfaction. I hear a lot of cases in which patients claim to be suffering from poor peripheral conversion of T4 into T3. Usually there is no supporting evidence and it is a diagnosis of exclusion in someone wh...

I'm sorry but I cannot allow this assassination of the TSH test to go without comment. The scientific and medical literature contains many hundreds of authoritative articles that attest to its proven clinical value. If it is as bad as you say then why were more than 20 million TSH tests performed in...

Galathea, For reading on the non-thyroidal illness syndrome I suggest that you read Chapter 5b of the Thyroid Manager (http://www.thyroidmanager.org). This Chapter gives an explanation of the syndrome illustrated by some of the conditions with which it is associated. There is also a balanced conside...

I am happy to pick up this chain of messages. The reality is that thyroxine does work for hundreds of thousands of people in the UK. If it works for them then of course, they are happy and they do not complain. There are a small number of people for whom the optimisation of thyroxine replacement pro...

A high concentration of TPO antibodies is a marker of autoimmune disease within the thyroid gland. It provides a marker of risk of progression from normal thyroid status to having a thyroid disorder. In the case of primary hypothyroidism an increased level of TPO antibodies is a reason for closer mo...

The comparison of diabetes with primary hypothyroidism is interesting. It is worth noting that no matter how severe the symptoms a diagnosis of diabetes cannot be made without clear biochemical evidence of abnormal glucose metabolism. Both diabetes and primary hypothyroidism are commonly seen in the...

Thank you ipman. There are peer reviewed publications examining the relationship between long term TSH suppression and the impact on bones and heart. The results of these studies are not completely consistent because it seems to depend on the initial thyroid disease, the method of treatment, the len...