P-wave dispersion in endogenous and exogenous subclinical hyperthyroidism.

BACKGROUND: The aim of this study was to measure maximum P wave duration (Pmax) and P wave dispersion (PWD), which can be indicators for the risk of paroxysmal atrial fibrillation when increased, and to reveal their relationship with thyroid hormone levels in patients with endogenous and exogenous subclinical hyperthyroidism. METHODS: Seventy-one patients with sublinical thyrotoxicosis (34 endogenous, 37 exogenous) and 69 healthy individuals were enrolled in the study. Pmax and minimum P wave duration (Pmin) on electrocardiogram recordings were measured and PWD was calculated as Pmax-Pmin. RESULTS: Pmax (p<0.001) and PWD (p<0.001) values were significantly higher in patients with endogenous subclinical hyperthyroidism compared with the control group. Pmax (p<0.001) and PWD (p<0.001) values were significantly higher in patients with exogenous subclinical thyrotoxicosis compared with the control group. Pmax (p=0.710) and PWD (p=0.127) were not significantly different in patients with endogenous subclinical hyperthyroidism compared with exogenous subclinical hyperthyroid patients. Pmax and PWD negatively associated with TSH in endogenous and exogenous subclinical hyperthyroidism. CONCLUSION: In the present study, we observed that Pmax and PWD were longer in patients with endogenous and exogenous subclinical hyperthyroidism. Lack of a difference in Pmax and PWD between patients with endogenous and exogenous subclinical hyperthyroidism seems to support the idea that hormone levels rather than the etiology of thyrotoxicosis affect the heart.

Effect of very low LDL-cholesterol on cortisol synthesis.

BACKGROUND: Cardiovascular disease is the most common cause of mortality around the world. The relationship between coronary artery disease and serum LDL-cholesterol levels has become obvious in recent years and statin treatment has been used more commonly. However, influence of intensive statin treatment on steroidal hormonal functions has remained unclear. In this paper, we evaluated the effect of very low LDL levels (<70 mg/dl) on serum cortisol concentrations, which is mainly synthesized from cholesterol. SUBJECTS AND METHODS: Forty-one patients with serum LDL-cholesterol levels below 70 mg/dl were included in the study. The control group consisted of 38 healthy people. Adrenal axis was evaluated by means of cortisol response to 1 microg ACTH test. RESULTS: The mean age of patients was 52.45+/-10.74 yr. Of 41 patients, 19 (46.9%) were female. There were statistically significant differences between the study and control group according to their serum cholesterol and LDL levels. Main serum LDL levels were 58+/-11.4 mg/dl and 131+/-25.8 mg/dl in the study and control group, respectively. There were no statistically significant differences in response to 1 microg ACTH stimulation test at basal, 30 min and 60 min among both study and control group. Atorvastatin treatment was generally well tolerated. CONCLUSIONS: Our data reflect that having serum LDL-cholesterol levels below 70 mg/dl did not affect the adrenal axis function in terms of cortisol.