Platelet activation in subjects with subclinical hypothyroidism.

BACKGROUND: Coronary heart disease is the major cause of death in the developed world. Platelet activation and aggregation are central processes in the pathophysiology of coronary heart disease. Mean platelet volume (MPV), a determinant of platelet function, is a newly emerging risk factor for atherothrombosis. The present study was designed to evaluate levels of MPV in subclinical hypothyroidic subjects compared with euthyroidic subjects in a cross-sectional study. MATERIAL/METHODS: Thirty-six subclinical hypothyroidic subjects and 20 euthyroidic control subjects matched for age, gender, and body mass index were selected. RESULTS: Metabolic parameters and platelet counts were not different among the study groups (p>0.05). The level of MPV was significantly higher in the subclinical hypothyroidic group than in the euthyroidic group (9.9+/-0.9 fl vs. 9.2+/-0.7 fl, p<0.001). The anti-TPO levels positively correlated to MPV levels in the subclinical hypothyroidic group (p<0.05). CONCLUSIONS: These results suggest that subjects with subclinical hypothyroidism tend to have increased platelet activation. Increased platelet activity could contribute to increasing the risk of atherothrombotic complications in subclinical hypothyroidism.

The mean platelet volume in patients with essential and white coat hypertension.

Mean platelet volume (MPV), a determinant of platelet function, is a newly emerging risk factor for atherothrombosis. The risk profile of white coat hypertension has not yet been completely clear. The present study was designed to evaluate MPV in white coat hypertensive subjects compared with essential hypertensive patients and normotensive subjects. We selected 36 essential hypertensive patients, 36 white coat hypertensive subjects and 36 normotensive control subjects matched for age, gender, and body mass index. MPV was very significantly higher in essential hypertensives and white coat hypertensives than in normotensives (P < 0.00); it was also higher in essential hypertensives than in white coat hypertensives (P < 0.05). Platelet counts were not different among the study groups (P > 0.05). MPV was positively correlated with ambulatory diastolic blood pressure in essential hypertension and white coat hypertension groups (P < 0.05). In conclusion, our data suggests one possible mechanism by which white coat hypertensive subjects may be at increased cardiovascular risk.

Hypocalcemic cardiomyopathy due to untreated hypoparathyroidism.

Hypocalcemic cardiomyopathy due to hypoparathyroidism is a very rare condition which is usually refractory to conventional treatment for cardiac failure but which responds favorably to restoration of normocalcemia. A 55-year-old man and a 46-year-old woman with a history of postoperative hypoparathyroidism presented with symptoms of cardiac failure and hypocalcemia. A presumptive diagnosis of dilated cardiomyopathy was considered by echocardiography and endomyocardial biopsies were consistent with cardiomyopathy. The coronary angiograms were normal and there was no apparent cause for dilated cardiomyopathy in these patients. The history of the patients and partial recovery of cardiac function after restoration of normocalcemia suggest that hypocalcemia was the cause of dilated cardiomyopathy.