Platelet cytosolic free calcium concentration and parathyroid hormone: changing relationships with haemodialysis in end-stage renal disease

Ambulatory blood pressure monitoring in renal dialysis and transplant patients

Blood pressure (BP) elevation and left ventricular hypertrophy are important factors in the high cardiovascular mortality rate in patients on the renal replacement program. Ambulatory BP monitoring is widely regarded as superior to random BP monitoring in predicting end-organ damage from elevated BP. One hundred seventeen patients (60 on hemodialysis [35 with long sessions and 25 with short sessions], 29 on continuous ambulatory peritoneal dialysis, and 28 transplant recipients) underwent ambulatory BP monitoring, with target organ assessment by electrocardiography. Mean 24-hour BP for the patients with the long hemodialysis sessions (LHD) was 115.5/66.6 mm Hg, without the regular use of antihypertensive drugs. The parathormone (PTH) level was the major determinant of BP on ambulatory BP monitoring analysis, with interdialytic weight gain and age each having weaker associations. The BPs of the other three patient cohorts were much higher (short hemodialysis session [SHD], 143.2/82.1 mm Hg; continuous ambulatory peritoneal dialysis, 137.1/76.8 mm Hg; transplant recipients, 135.9/79.2 mm Hg). Overall, two thirds of the patients had reduced diurnal BP variability. Electrocardiogram voltage criteria for left ventricular hypertrophy were exceeded in approximately one third to one half of the patients. Our findings show that good control of BP is possible without recourse to antihypertensive drugs in the context of dialysis with slow ultrafiltration.

Blood pressure reduction after parathyroidectomy for secondary hyperparathyroidism: further evidence implicating calcium homeostasis in blood pressure regulation

A link between plasma calcium, dietary cations, and blood pressure has been suspected for some time, with human, experimental animal, and epidemiological data adduced to support this hypothesis. We identified 21 patients receiving regular maintenance hemodialysis, but not receiving any regular antihypertensive treatment, who had undergone 22 surgical removals of the parathyroid glands in the period 1978 to 1992. These patients' records were then scrutinized. The group preparathyroidectomy mean systolic blood pressure (BP) was 142.6 +/- 19.4 mm Hg. After the operation, the mean systolic BP was 133.6 +/- 21.9 mm Hg (P = 0.004). Plasma calcium decreased from 2.72 +/- 0.18 mmol/L to 2.52 +/- 0.19 mmol/L (P < 0.001). There was a correlation between the decreases in systolic blood pressure (SBP) (9.4%) and plasma calcium (7.3%); r = 0.60, P = 0.012. The decrease in SBP was not immediate, but delayed some months and complete by approximately 9 months after the operation. Furthermore, using ambulatory BP monitoring in a group of long-term hemodialysis patients, we found that parathyroidectomized patients had lower BP and pulse rates than those with intact parathyroid glands (SBP, 122.9 +/- 16.3 mm Hg v 102.9 +/- 9.9 mm Hg; pulse rates, 87.5 +/- 12.7 v 72.0 +/- 7.5 beats/min, P < .001, nonparathyroidectomy v postparathyroidectomy, both comparisons). These data support a link between plasma calcium and BP in patients receiving maintenance hemodialysis.