Analysis of the familial aggregation of hypertension among patients with different types of kidney stone disease

grantor: University of TorontoBackground. Past studies identified an association between kidney stone (KS) disease and hypertension (HTN). The aims of the present thesis are to determine whether there is a specific biochemical abnormality that is responsible for the association and whether the association has familial determinants. Methods. Two hundred and twelve KS patients (age 18-50 years) were classified into six diagnostic categories on the basis of their most prominent urinary metabolic abnormality, and were interviewed about the occurrence of HTN among their first-degree relatives. Familial aggregation of HTN was assessed by the comparison of the prevalence of strong family history (FHx) of HTN among the categories and by the comparison of prevalence of HTN among the fathers, mothers and siblings of the patients from the different diagnostic groups. Results. The prevalence of positive FHx of HTN was significantly higher in patients with hyperuricosuric KS disease (OR = 3.8 (1.22-11.66)), and the prevalence of HTN was significantly higher in siblings of the hyperuricosuric patients compared to the siblings of all other patients (OR = 3.8 (2.12-6.67)). The association was independent of the presence of HTN in the probands. Sub-group analysis among the hyperuricosuric patients revealed that it was those patients who had hypercalciuria in addition to hyperuricosuria that had positive FHx of HTN (OR = 9.0 (1.74-46.6)) and siblings of only these patients had significantly more HTN (OR = 5.5 (2.02-15.15)). These combined hyperuricosuric/hypercalciuric patients had higher serum levels of uric acid and higher urinary excretion of sodium and phosphorus besides the hyperuricosuria and hypercalciuria. Conclusion. That there is familial aggregation of HTN among KS patients who have high urinary excretion of uric acid especially when combined with hypercalciuria.M.Sc

Measurement of pulse wave velocity in children and young adults: a comparative study using three different devices

To estimate the value of pulse wave velocity (PWV) in pediatric cardiovascular disease, prospective studies are needed. Various instruments based on different measurement principles are proposed for use in children, hence the need to test the comparability of these devices in this younger population. The objective of this study was to compare PWV measured by oscillometry (Vicorder (VIC)) with the gold standard of applanation tonometry (PulsePen (PP), Sphygmocor (SC)). PWV was measured in 98 children and young adults (age: 16.7(6.3-26.6) years (median(range)) with the above three devices at the same visit under standardized conditions. Mean PWV measured by VIC was significantly lower than that measured by SC and PP. There was no difference following path length correction of the VIC measurement (using the distance between the jugular notch and the center of the femoral cuff), (PP: 6.12(1.00), SC: 5.94(0.91), VIC: 6.14(0.75) m s(-1)). Velocities measured by the three devices showed highly significant correlations. Bland- Altman analysis revealed excellent concordance between all three devices, however, there was a small but significant proportional error in the VIC measurements showing a trend toward lower PWV measured by VIC at higher PWV values. Our study provides data on the three most frequently used instruments in pediatrics. Following path length correction of the VIC, all three devices provided comparable results. Thus, our work allows extrapolating data between previously established normal PWV values for children and forthcoming studies using these instruments to assess children at long-term risk of cardiovascular disease. The small proportional error of VIC needs additional technical development to improve the accuracy of the measurements.Hypertension Research advance online publication, 28 July 2011; doi:10.1038/hr.2011.103