Does Subclinical Hypothyroidism Cause Diastolic Heart Failure?
Subclinical hypothyroidism is a condition in which the thyroid gland is having trouble producing enough thyroid hormone, so the thyroid gland requires higher levels of "thyroid stimulating hormone" (TSH - the hormone that "whips" the thyroid gland into doing its work). In patients with subclinical hypothyroidism, the actual amount of thyroid hormone in the blood is normal - but levels of TSH are elevated. Previous studies have suggested that patients with subclinical hypothyroidism have a higher risk of heart disease. What is new about this latest study is that it identifies subclinical hypothyroidism as a potentially important cause of diastolic heart failure.
In diastolic heart failure, the pumping function of the heart is largely normal, but the ability of the heart to fill with blood before it pumps is impaired. Doctors have been puzzled about the cause of diastolic heart failure. The possibility that subclinical hypothyroidism may cause diastolic heart failure is an attractive one. First, it turns out that the kind of people who develop diastolic heart failure - middle aged or older women - are the same kind who tend to develop subclinical hypothyroidism. And second, subclinical hypothyroidism is a treatable condition. (It is treated the same way that "clinical" hypothyroidism is treated - with thyroid replacement hormone pills.)
At this point, it is not proven that subclinical hypothyroidism causes heart disease. However, the evidence grows ever stronger. Women whose TSH levels are 10.0 mIU/L or higher should certainly discuss with their doctors whether treatment is in order.
You can read more about the thyroid and heart disease here.
You can read more about thyroid disease here.
Sources:
Rodondi N, Bauer DC, Cappola AR, et al. Subclinical thyroid dysfunction, cardiac function and the risk of heart failure. The Cardiovascular Health Study. J Am Coll Cardiol 2008; 52: 1152-1159.
Comments
The old level for tsh was .5 to 5 . Most labs have lowered normal levels of TSH to .3 to 3. My daughter and I have found that we both feel best at around 1. Actually 1 or under. If I’m above one I still have symptoms. I was diagnosed with hypothyroid when my TSh was at 6. I had previously been tested and my level was 4.29 but the lab still was using the old values then which was .5 to 5. So they didnt treat me. It was 2 years and a heart attack that it was at 6 and at that time the lab did use the lower levels. I cant help but wonder if I had been treated years before if I would have avoided the heart problems.