Nutrition and growth in children with chronic renal insufficiency
Practical joint dietetic/medical guidelines are required for children with differing levels of severity of chronic renal insufficiency (CRI). This thesis describes the current dietetic/medical package of care provided within a specialised paediatric renal unit, and provides an insight into considerations for future clinical guidelines. Children were grouped at baseline following [51Cr]-labelled EDTA glomerular filtration rate (GFR, m1/min/1.73m2) estimations, into 'normal' kidney function [GFR > 75, mean 106 (SD 19.5), n=58], providing baseline data only, mild (GFR 51-75, n=27), moderate (GFR 25-50, n=21) and severe (GFR < 25, n=19) CRI. Those with CRI were followed for two years and 51 children completed the study (19 mild, 19 moderate, 13 severe CRI). Baseline and 6 monthly measurements of anthropometry, blood pressure, laboratory investigations and yearly dietary intakes (3-day semi-quantitative diaries) were obtained. EDTA GFR's were compared to estimations of GFR using serum cystatin C and plasma creatinine/height concentrations. Amongst the findings, mean standard deviation scores (SDS) for all anthropometric markers deteriorated with worsening renal function at baseline, from mean SDS for weight, height, body mass index and mid upper arm circumference in 'normal' children of O.28 (SD 1.0), 0.19 (SD 1.0),0.21 (SD 1.1) and 0.39 (SD 1.0) respectively, to values of -1.32 (SD 1.0), -1.55 (SD 1.1), -0.44 (SD 1.1) and -0.58 (SD 0.9) in severe CRI. Over two years, mean height SDS significantly increased in children with severe CRI (p=0.003) and was maintained in mild and moderate CRI, despite deterioration in renal function. Correlation between changes in energy intake and height SDS was observed in severe CRI (r2=0.5, p=0.001). From individual observations and correlation, higher phosphate and sodium intakes appeared to be associated with greater deterioration in estimated GFR in children with mild CRI. An inverse correlation between calcium intake and plasma parathyroid hormone was observed in severe CRI (r2=0.27, p=0.065). Disturbances in nutritional intakes, bone biochemistry and growth occurred early in the course of CRI and deterioration in renal function, as determined by estimated GPR, was greatest in those with mild CRI. Regular joint dietetic/medical intervention is likely to be beneficial in children with mild and moderate CRI, in addition to those with more severe CRI, to both correct initial disturbances and reduce the chances of progression.