Increased Risk for Atherosclerosis Estimated by Pulse Wave Velocity in Hypothyroidism and its Reversal with Appropriate Thyroxine Treatment

Pulse wave velocity (PWV) is known to represent arterial stiffness and is established as a marker for cardiovascular risk and a prognostic factor for mortality in the case of chronic renal failure or hypertension. The application of an automated apparatus for measuring brachial-ankle pulse wave velocity (baPWV) has made PWV measurement non-invasive, easier to screen for cardiovascular risk and as a result, baPWV measurements have become widely applied in clinical practice in recent years. We assessed the baPWV in 7 flank hypothyroidism patients and 28 subclinical hypothyroidism patients. In comparison with age matched healthy controls, 3 hypothyroid patients had advanced values and by replacement therapy, all 7 subjects showed improvement in their baPWV values (1531.2 +/- 242.7 to 1330.2 +/- 208.6 cm/s, p<0.05). In 28 subclinical hypothyroid subjects, 71% also had accelerated baPWV values for their age. Ten subjects (36% of all) had neither hypertension, hyperlipidemia, diabetes nor were taking any medication, and yet 8 patients out of 10 showed advanced baPWV values compared to age matched mean values. The baPWV was not correlated to TSH or total cholesterol levels, and was associated with only age and blood pressure (p = 0.01, <0.001, respectively), which are widely demonstrated as the characteristics for baPWV. In two subclinical hypothyroid subjects, who were normotensive and had no dyslipidemia, thyroxine treatment was performed and the baPWV decreased with unchanged blood pressure and total cholesterol levels. We concluded that the arterial wall stiffness tends to be increased in both overt and subclinical hypothyroid patients, and an appropriate treatment could reverse the abnormalities. It is possible that the initiation of adequate treatment in subclinical hypothyroidism may reduce the cardiovascular risk.