A great warning from the British Thyroid Association

There is a great divide, I think, between doctors on this side of the Atlantic, particularly physicians in the US, and doctors in Europe (especially doctors in the UK), and that divide involves how - and where - we see disease.

Thus, in North America, and very particularly in the USA, there is a real tendency to see disease - to diagnose problems - long before they present as real problems for the patient, while in the UK, they tend to wait to diagnose a condition until it's begun to affect someone with evident symptoms or signs.

In other words, doctors in the US tend to test, test, test ("It's only a paper cut, Bob, but let's do a CT scan just to be safe." "Gee, thanks for being so thorough, doc.") and when we test, test, test, we pick up a lot of deviations from normal even though those deviations (abnormalities?) don't actually mean anything and they certainly don't bother the patient.

What does all this have to do with the thyroid?

Well, in North America, there has been a great increase in the diagnosis of a condition that has been called "pre-hypothyroidism", that is, the patient has no real symptoms of low thyroid function, but on a thyroid blood test, they register with a slightly low thyroid hormone level.

The reason that matters a lot is that some experts argue that all these people with somewhat low thyroid hormone levels but no symptoms (a whopping 10-15 % of an aging population) should be treated - for the rest of their lives - with thyroid hormone replacement therapy because once thyroid hormone levels starts to sink, they will never recover on their own, and really low thyroid hormone levels have been linked to a host of significant potential problems including a raised risk of heart disease.

In other words, for North American docs, hypothyroidism is a defined medical condition with known medical risks, and pre-hypothyroidism is the first step on that road: it's a presumed medical condition with presumed risks similar to those of actual hypothyroidism.

Doctors in the UK have by-and-large laughed off this diagnosis, and especially its treatment with the twin arguments that 1) no one can really prove that "pre-hypothyroidism" is a real condition, and 2) even more important, there is no proof that treating a somewhat low thyroid hormone level makes any difference in prognosis, and especially no difference in lowering the risk of heart disease, which is what this latest warning from the British Thyroid Association is all about: namely, that there are potential risks to dispensing thyroid hormones much more widely, and very little proof as yet of benefit.