Tuesday, April 25, 2017

'Subclinical' Hypothyroidism is Being Over-treated

What was the most prescribed drug in 2016?   If you guessed a blood pressure medication, a cholesterol-lowering drug, insulin for diabetes, or even a painkiller such as oxycodone, you'd have been wrong.  It was levothyroxine, a drug used to treat hypothyroidism. But not all physicians are using this drug correctly; many are using it to treat 'subclinical' hypothyroidism.

Subclinical hypothyroidism is generally defined as a slightly elevated TSH (thyroid-stimulating hormone; indicating perhaps an under-responsive thyroid gland), accompanied by a number of vague and highly subjective symptoms such as tiredness, lack of motivation, and muscle aches and pains. It's called 'subclinical' hypothyroidism because levels of the two thyroid hormones, T3 and T4, are still normal, as opposed to true hypothyroidism in which there is a clear deficiency in these two hormones.

The problem is that many of the physical symptoms of hypothyroidism, such as tiredness and muscle aches and pains, are common complaints in older people.  So if their TSH levels are just a little over the normal level (which also often happens with age), physicians are increasingly putting their older patients on levothyroxine, regardless of what their T3 and T4 levels are.  As a result, fully 15% of older Americans are taking levothyroxine to treat their alleged symptoms.

However, recent evidence shows that other than lowering TSH levels to normal, levothyroxine doesn't have any effect on the actual "symptoms" patients are complaining about - no effect at all.  If this new evidence is correct, physicians could stop prescribing levothyroxine to treat 'subclinical' hypothyroidism entirely.  The proper use of levothyroxine is to treat patients with true hypothyroidism, in which T3 and T4 are demonstrably low.

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