Intradialytic serum protein concentrations differ between nightly nocturnal and conventional haemodialysis

Nocturnal haemodialysis (NHD) is a new haemodialysis (HD) modality that has been shown to have many benefits when compared with conventional haemodialysis (CHD). Previous results from our NHD programme have demonstrated a 7% fall in the postdialysis serum albumin concentration when compared with the pre-HD levels. A similar, physiological, 9% haemodilution of albumin is seen in normal individuals on assuming a supine posture.

In this observational study, the intradialytic change in the concentration of 11 serum proteins (total protein, albumin, alkaline phosphatase, gamma glutamyl transferase, alanine transaminase, amylase, transferrin, complement factors 3 and 4, free thyroxine and C-reactive protein (CRP)) was measured in 10 patients on NHD and in 10 age- and sex-matched controls on CHD. The ultrafiltration rate (UFR) was also recorded.

We demonstrated an intradialytic fall in the total protein (0.63%), albumin (2.40%), alkaline phosphatase (1.84%), amylase (8.82%), complement factor 3 (2.73%) and CRP (8.19%) in patients on NHD. This was of a lesser magnitude than that occurring in the pilot study but still approximated the physiological fall in serum proteins occurring with overnight recumbency in normal individuals. In contrast, all serum proteins measured rose during CHD, reflecting intravascular volume contraction and haemoconcentration. The UFR was significantly lower in NHD than CHD (234.52+/-20.90 mL/h vs 435.38+/-38.44 mL/h, P<0.001).

We concluded that NHD is a modality that facilitates the use of a low UFR and hence the slow removal of volume which, in turn, results in a minimal perturbation of the normal recumbent volume distribution mechanism and the partial preservation of the normal physiological response to recumbency of the serum protein concentration.