Introduction: Under physiological conditions kidneys work continuously, 168 h/week. In contrast, patients with end-stage renal disease are usually dialyzed only 12-15 h/ week. This unphysiological dialysis dose, even if considered adequate by current Kt/V-based dose estimates, is just capable to maintain the alterations of multiple metabolic parameters at a level that permits an unacceptable annual mortality rate of 10-20%, mainly due to cardiovascular events, protein energy wasting and infections.
Patients and methods: Thirteen haemodialysis patients were converted from conventional (3 x 4 h/week) to an intensified nocturnal (3 x 8 h/week) dialysis and were longitudinally followed up for 12 months. Different parameters were evaluated before treatment conversion and quarterly during the follow-up period [i.e. dialysis efficacy (eKt/V), mean arterial pressure (MAP), antihypertensive drug score, extra-cellular volume (ECV), haemoglobin, transferrin saturation, ferritin, dose of erythropoiesis-stimulating agents (ESA), iron requirement, parameters of nutrition (body weight (BW), albumin, protein, normalized protein catabolic rate (nPCR), bioelectrical impedance analysis (BIA)), C-reactive protein, calcium-phosphate product, alkaline phosphatase (AP), intact parathyroid hormone (iPTH) and amount of phosphate-binding pharmacotherapy].
Results: The calculated dialysis efficacy rose after switching the treatment mode (eKt/V 1.87 versus 2.7, P < 0.0001). Further, a significantly decreased MAP in the pre- (100 versus 89 mmHg) and postdialytic period (97 versus 83 mmHg), and a decreased ECV (13.8 versus 13.2 L; P = 0.03) even though antihypertensive pharmacotherapy could be substantially reduced (P < 0.0001), was found. Concomitant with a reduction of ESA (66.5 versus 45.2 IU/ kg/week; P = 0.006), the haemoglobin level rose significantly (11.4 versus 12.5 g/dL, P = 0.01). Nutritional status assessed by BW (70.9 +/- 20.2 versus 72.1 +/- 19.8 kg, P = 0.02), nPCR (1.39 versus 2.25 g/kg/day, P = 0.02) and BIA (phase angle: 6.2 versus 6.9 degrees, P < 0.001) improved. The calcium-phosphate product slightly declined, without changes in the dose of any phosphate binders. Surprisingly, iPTH of those patients with intact parathyroid glands (n = 7) increased approximately 3-fold (27.9 versus 59.35 pmol/L, P = 0.009), while the AP was found stable.
Conclusion: This study demonstrates improvements in numerous dialysis-associated metabolic variables after intensification of HD time. Of note, an increase of iPTH was detected in those patients with intact parathyroid glands.