Double-blind randomized, crossover trial of calcium supplementation in essential hypertension.

In a double-blind, randomized, placebo-controlled, crossover trial, 23 middle-aged patients with mild to moderate essential hypertension were given an oral calcium supplement (1 g/day) for 8 weeks. At the end of this period, eight patients continued with this treatment for an additional 2 weeks but were also given 0.5 micrograms/day of 1,25-(OH)2 vitamin D3. In the 21 patients who completed the study, arterial pressure during the calcium-supplemented phase was almost identical to that of the placebo phase. In eight patients, mean arterial pressure (MAP) had changed by greater than 5 mmHg at the end of the calcium-supplemented period, compared with the end of the placebo phase (six patients showed an increase in MAP and two a decrease). Changes in arterial pressure were unrelated to age, plasma ionized calcium, parathyroid hormone (PTH), plasma renin activity (PRA), plasma aldosterone, 24-h urinary calcium, sodium and potassium and were only weakly related to body weight. In the eight patients who continued with the treatment of calcium plus 1,25-(OH)2 vitamin D3 after the 8-week study period, arterial pressure changed very little and not significantly. These results do not support the suggestion that calcium supplements lower arterial pressure in middle-aged subjects with mild to moderate essential hypertension.

The effect of dialysate temperature on haemodialysis leucopenia.

We assessed the influence of dialysate temperature on intra-dialytic leucopenia. Lowering dialysate temperature from 38 degrees C to 20.5 degrees C caused a decrease in the dialysis associated white blood cell reduction from 82 +/- 6 per cent to 32 +/- 19 per cent. The degree of leucopenia bore a highly significant relationship with dialyser blood temperature suggesting that a further lowering of blood temperature (to about 20 degrees C) would almost entirely prevent intra-dialytic leucopenia.