An approach to protein restriction in children with renal insufficiency

Dietary adherence in children with chronic kidney disease: a review of the evidence

BACKGROUND

In children with chronic kidney disease (CKD), a nutrition support plan is important to ensure optimal macro- and micro-nutrient intake in order to avoid malnutrition, disease-related complications and growth rate reduction. Children with CKD and their families encounter many difficulties in adjusting to the renal diet. Even though adherence to the recommended dietary plan is important in CKD, it is rarely measured partly due to the lack of robust, unbiased assessment methods.

METHODS

In this review of 22 papers, the techniques used to assess adherence in children with CKD are reviewed, alongside their advantages and disadvantages.

FINDINGS

Although dietary surveys, biochemical index assessment and clinician ratings have been found not to be efficient when used as a single tool, they should be used in combination in order to give the opportunity to the health providers to perceive adherence from as many angles as possible.

Nutritional status, protein intake and progression of renal failure in children

Nutritional status and progression of renal failure in 35 children (22 males and 13 females; mean age: 8.85+/-4.13 years) with moderate renal failure were followed for 2 years. All children were on an "ad libidum" diet. Protein intake was determined by a minimum of two dietary diaries kept by the parents and the appearance of urea nitrogen. The children were divided into two groups according to their protein intake: Group 1 - sub-optimal intake (46% of the children, all with significantly lower protein intake); Group 2 - adequate protein intake. The mean protein intake (expressed as a percentage of the WHO recommendations) based on the diets of the patients was 94.79% in Group 1 children and 175.45% in Group 2 children (p<0.05). All patients had a calorie intake of at least 80% of the WHO recommendations. Nutritional status was determined by anthropometric measurements expressed as a standard deviation score. There was no significant anthropometric or biochemical evidence of malnutrition in children with moderate chronic renal failure (CRF). The glomerular filtration rate (GFR) in patients with a sub-optimal intake of protein was -5.41+/-2.87 ml/2 year versus-9.53+/-8.61 ml/2 year in the normal protein intake group. There was no correlation between protein intake, nutritional status and progression of renal failure in children with moderate CRF within the 2-year study period.

Improved renal function following aggressive treatment of urolithiasis and concurrent mild to moderate renal insufficiency

To our knowledge the prevalence of urinary stone disease and concurrent mild to moderate renal insufficiency has never been reported. A review of our last 2,000 urinary stone patients identified 33 (1.65%) with serum creatinine levels of 2.0 mg./dl. or greater at presentation. Chemical composition, location and complexity of the calculi, types of procedures required to render the patient stone-free and the effect of surgical intervention (independent of relief of obstruction) on renal function were evaluated. Mean serum creatinine level before surgical intervention and after placement of a ureteral stent or percutaneous nephrostomy tube in patients with evidence of obstruction was 3.2 mg./dl. (range 2.0 to 7.5). Complete or partial staghorn calculi were found in 21 of the 33 patients (64%), including 8 with bilateral staghorn calculi. Seven patients required 1 procedure, 1 required urinary alkalization alone and the other 25 required an average of 3.5 procedures each. Stone analysis revealed struvite, mixed calcium and uric acid to be the most common types. Followup creatinine values (the latest available within 1 year) and corresponding creatinine clearances showed remarkable improvement. The mean decrease in serum creatinine level was 1.2 mg./dl. (p < 0.001). There was no statistically significant difference in the rate of decrease between patients with pretreatment serum creatinine levels of 2.0 to 2.9 mg./dl. and those with initial values of 3.0 or more. Renal calculi and concurrent mild to moderate renal insufficiency warrant aggressive treatment. Patients demonstrate significant improvement in renal function independent of relief of obstruction.

The effect of growth hormone on growth and blood urea levels in children with chronic renal failure

It has been claimed that low protein diets slow deterioration of chronic renal failure (CRF) by reducing renal solute load. The anabolic effect of recombinant human growth hormone (rhGH) also has potential to reduce renal solute load and thereby slow progression of renal failure. The aim of this study was to determine the effect of rhGH on growth, renal solute load and renal function in children with CRF. Seven prepubertal children, aged 2-14 years, with moderately severe CRF (creatinine clearance 7.7-23.4 mL/min per 1.73m2) were treated with daily subcutaneous rhGH, 1 U/kg per week for 10-12 months. As expected, mean height velocity standard deviation scores (SDS) increased, from -2.87 before treatment to +3.39 on rhGH, and mean height increased from -3.1 to -2.4 SDS. Serum urea concentrations decreased in most patients during the first month of growth hormone treatment from a mean of 20.0 +/- 7.7 mmol/L to 14.8 +/- 5.8 mmol/L (P = 0.006). The serum urea then returned to pretreatment levels over the next few months. In the 12 months before treatment with growth hormone, mean creatinine clearance decreased from 19.3 mL/min per 1.73 m2 to 16.7 mL/min per 1.73 m2. In the next 12 months on rhGH mean creatinine clearance decreased further to 13.5 mL/min per 1.73 m2. Therefore the rate of deterioration of renal function was unaffected during treatment with growth hormone. Initial treatment with rhGH is associated with decrease in serum urea concentrations in children with CRF, probably mediated by stimulation of anabolic incorporation of dietary nitrogen into body protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Low-protein diet in children with chronic renal failure--1-year results. European Study Group for Nutritional Treatment of Chronic Renal Failure in Childhood

In 1988 the European Study for Nutritional Treatment of Children with Chronic Renal Failure started its multicentre randomized trial to investigate the influence of protein intake on the progression of renal failure. A total of 284 children had been registered. Of these 221 were accepted for the study. The data from 105 patients after 1 year of study are available for preliminary analysis. Fifty children were randomized for the diet group and 55 for the control group. Both groups were comparable concerning age, glomuerlar filtration rate (GFR) and height standard deviation score for chronological age at the start of the study period and the distribution of primary renal diseases and sex. Limits for protein and energy intake were set according to the safe levels and recommendations given by the World Health Organization. The compliance with dietary prescriptions as calculated from dietary diaries was good. A low-protein diet did not do any harm to the children with respect to length gain and weight gain. The progression of renal failure was minimal in the diet group (mean loss of GFR 3.6 ml/min per 1.73 m2 per year) as well as in the control group (2.3 ml/min per 1.73 m2 per year). The differences between the diet group and the control group were statistically not significant when either all patients or only subgroups of various primary renal diseases were analysed. When only patients with a good compliance were considered (documented by dietary diaries or by urea nitrogen excretion) the same results were obtained. In summary, reduction of protein intake was accepted by the majority of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Progressive renal insufficiency in methylmalonic acidemia

Methylmalonic acidemia is a heterogeneous inborn error of propionate metabolism. Therapy frequently includes a low-protein diet to minimize precursors of methylmalonic acid (MMA) and reduce its concentration in body tissues. Renal dysfunction in these patients is increasingly recognized. Tubulointerstitial disease has been found in the small number of renal biopsy specimens from young children previously reported by others. We describe an 18-year-old patient with the mut- form of the disease who developed renal dysfunction despite the use of a low-protein diet. Tubulointerstitial injury was documented by renal biopsy. The patient had no risk factors associated with established causes of chronic tubulointerstitial nephropathy (CTIN). We postulate that methylmalonyl-CoA and/or its precursors (propionyl-CoA, odd-chain fatty acids), may be capable of producing CTIN. We speculate that prevention of renal injury may require lower tissue levels of MMA and its precursors than those required for prevention of ketoacidosis.