Views & Reviews From the Frontline

Bad medicine: thyroid disease

BMJ 2012; 345 doi: (Published 09 November 2012) Cite this as: BMJ 2012;345:e7596

Re: Bad medicine: thyroid disease

This article is disturbing in that many thyroid patients testify to not being diagnosed early enough and then being kept on levothyroxin doses that they later discover are too low.

The reference ranges in the US are wider because they need to be. Thousands of thyroid patients are not properly diagnosed each year in the UK. Further, we overly rely on blood chemistry and the inter relation of TSH and free T4 levels. The test is held up as the "gold standard". However the test is fallible in two ways. Firstly it does not show the free T4 levels in body tissue or in the brain. Secondly it does not show whether FT4 is converting properly into FT3 or whether the patient has a gene variation that might interfere with this process or subsequent treatment with synthetic T4. GPs are reluctant to diagnose on the basis of clinical symptoms as well as blood chemistry because of an overly reliance on evidence based medicine. The problem here is that the evidence might be wrong or missing - not the full picture.

"The epidemiology is poorly studied, but evidence suggests that subclinical hypothyroidism spontaneously corrects in 80% of patients in two years." This worries me. The author seems prepared to allow patients to wait two years before treated in the hope they will get better by themselves? I have first hand experience of patients who have failed to be diagnosed and in the absence of a diagnosis no management of the condition was recommended. On anecdotal evidence the situation is not uncommon. Those individuals later find GPs who are prepared to try low doses of thyroxin sodium to good effect. Indeed rather than there being an over diagnosis it is more likely - given the flawed testing techniques and over caution - that there is an under diagnosis. We just don't know. Either way. What we do know is that the medical establishment in the UK are not prepared to entertain the notion that we might be under diagnosing patients with thyroid issues.

Competing interests: No competing interests

13 November 2012
R C Reade
London W5