Daily on line haemodiafiltration promotes catch-up growth in children on chronic dialysis

In children, growth can be used as a measurable parameter of adequate nutrition and dialysis dose. Despite daily administration of recombinant human growth hormone (rhGH), growth retardation remains a frequent problem in children on chronic dialysis. Therefore, we performed an observational prospective non-randomized study of children on in-centre daily on line haemodiafiltration (D-OL-HDF) dialysis with the aim of promoting growth.

Mean age at the start of the study was 8 years and 3 months, and all children had been receiving rhGH treatment for >12 months before enrolment. Mean follow-up time on D-OL-HDF was 20.5 +/- 8 months (range, 11-39 months). Renal residual function was either <3 mL/min/1.73 m(2) or anuric. Vascular access was a fistula (13/15) or a central venous catheter (2/15). Dialysis was delivered daily, six days a week in 3 hourly sessions (18 h/week), in a predilution OL-HDF mode, allowing a high convective volume (18 to 27 L/m(2) body surface area per session), Kt/V(urea) on line measured at least 1.4 per session.

Mean growth velocity increased from 3.8 +/- 1.1 cm/year at inclusion to 14.3 +/- 3.8 cm/year during the first year of D-OL-HDF, resulting in a change in height standard deviation score (SDS) over the follow-up period from -1.5 +/- 0.3 SDS to +0.2 +/- 1.1 SDS. Increase in body mass was also noted without impaired control of blood pressure. Time-average deviation for urea (TAD(urea)) was low at 2.5 +/- 0.4 as was TAD(bicarbonate) due to the normal pre and post dialysis bicarbonate levels, respectively, 23.6 +/- 0.5 mmol/L and 26.6 +/- 0.5 mmol/L. The absence of any dietary restrictions permitted a mean protein diet intake (PDI) of 2.5 +/- 0.2 g/kg/day (PDI measured from a 3-day diet survey), contrasting with a mean normalized protein nitrogen appearance (nPNA) of 1.53 +/- 0.12 g/kg/day (nPNA calculated from urea dialytic kinetic). A low C-reactive protein was noted in 13/15 children, and mean beta(2) microglobulin was low, 15.3 +/- 0.3.3 mg/L.

Daily OL-HDF promotes catch-up growth in children despite on chronic dialysis. This catch-up growth if continued, should allow the children to reach their mid-parental target height in the future. It could be speculated that the improved response to rhGH is the result of several combined factors conducting to less malnutrition and to less cachexia.