The problem here, actually, is that peripheral de-iodination from T4 to T3 becomes less efficient with ageing, and so it is inappropriate to use the same reference intervals for T4 in the over-60's as we do for the rest of the population. This is in the literature, but generally ignored. Older subjects need more T4 to make the same amount of T3. They also may have pituitary insensitivity to feedback control (everything wears out as you get older, believe me) and hence are less likely to elicit a TSH response to inadequate thyroid hormone production. 

Comments about the staggering incompetence and arrogance of lab staff when dealing with the problems of actual people do ring a bell, but I must agree that T3 measurement adds nothing to the diagnostic process, except when you encounter hyperthyroidism with normal T4 levels.

Finally, I've seen a case just like the one Tim describes. She had a sub-total thyroidectomy after a thyroid storm and sustained a TSH of c. 360 for 6 months (after which it came down). I used her serum as a control for years afterwards!

Nick Miller
London

On 10 September 2014 09:12, Sharpe, Peter <[log in to unmask]> wrote:

Dear Colleagues,

 

When I came to this Trust in 1998, I was the first Chemical Pathologist to be appointed. Before this a Haematologist with an interest in Clinical Biochemistry had been looking after the service.

 

A routine thyroid profile consisted of both fT4 & fT3 plus TSH.  I’m unsure as to the reasons for this other than “historical”.

 

Within a few months, after widespread consultation with all requestors including Endocrinologists, we removed the routine fT3 measurement. It became clear that fT3 was adding very little (if anything) to the interpretation of thyroid profile results. fT3 can still be specially requested and we do run it under certain circumstances, but the numbers have dwindled to a few per week.

 

My Endocrinology colleagues remain very sceptical about the so called diagnosis of low fT3 syndrome.

 

Best wishes

Peter

 

Dr Peter Sharpe

Consultant Chemical Pathologist

Associate Medical Director, Research & Development

Southern Health & Social Care Trust

Chair RCPath NI Regional Council

Ext: 60869

Tel: 028 38360696

Fax: 028 38334582

 

From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of Peter Beresford
Sent: 09 September 2014 16:19
To: [log in to unmask]
Subject: Low T3 syndrome

 

Dear Mailbase,

 

We have received calls from GPs who have been approached by a number of patients regarding the article below, which was published in the Daily Mail last week.  

 

http://www.dailymail.co.uk/health/article-2734215/Cold-hands-Always-tired-It-hidden-thyroid-problem-doctors-refuse-treat.html

 

The subject of the article is ‘Low T3 syndrome”, and it suggests to patients that they require FT3 measured routinely in addition to FT4, as well as opening up a debate with regards to treatment with T3.  The article quotes respectable Endocrinologists quoted both for and against (although I suspect some of their comments may have been taken out of context). 

 

I would be interested to know if others have also been approached in response to this article and what guidance has been given to GPs responding to these queries. 

 

The guidance documents available on the British Thyroid Association website (http://www.british-thyroid-association.org/Guidelines/ ) are very helpful, but recognising that this is a complex area I wonder if anyone is aware of any more recent evidence or guidelines about the role of T3 in the aetiology and treatment of hypothyroidism?

 

Best wishes

 

Peter

 

Peter Beresford

Consultant Clinical Scientist

Southmead Hospital

 


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