Claire Kleinknecht

Membranous glomerulonephritis and hepatitis B surface antigen in children

Of 33 children with membranous nephropathy screened for HBs Ag, 14 were found to be HBs Ag carriers, whereas HBs Ag was detected in 3 of 170 and 4 of 100 children with glomerular and nonglomerular kidney diseases, respectively. HBs Ag was often associated with acute hepatitis at onset (five patients) or with elevated transminases values. This high incidence and the prevalence of an unusual subtype (ayw2) suggest a relationship between HBs Ag and the glomerular lesions. Using immunofluorescence, however, HBs Ag could not be detected within the deposits, so that the nature of the relationship cannot be considered as established. The clinical outcome (50% remission), the plasma complement component disturbances, and findings by immunofluorescence did not differ from those observed in children with MGN without detectable HBs Ag.

Primary distal tubular acidosis in childhood: Clinical study and long-term follow-up of 28 patients

The long-term follow-up of 28 patients with congenital primary tubular acidosis is described. Ten patients had affected siblings but no history of similar symptoms in the preceding generation. Deafness was associated in 14 patients and developed before 12 years of age. Deafness was present in all familial cases, and patients without deafness showed no familial incidence, suggesting the existence of two different entities. All patients had growth retardation, which was more severe in the older patients and was always markedly improved by alkaline therapy. Rickets was found in some patients but seemed related to vitamin D deficiency. Catch-up growth was limited to the first 2 years of therapy in patients treated before 2 years of age, but sometimes lasted longer in older patients. Of the 12 patients who reached adulthood, those without rickets achieved a normal height but the others did not. We believe that therapy should be continued throughout life because of the risk of nephrocalcinosis.

Growth in children treated with long-term hemodialysis

Linear growth and bone maturation have been studied in 17 children treated with regular hemodialysis for one to three years. Linear growth was normal in four children and retarded in 13. The adolescent spurt when present was markedly decreased. Statural and skeletal development were parallel except in: (1) children under eight years of age, (2) pubertal patients, and (3) those with severe osteodystrophy. In these instances, linear growth was impaired in relation to bone maturation. Three factors involved in growth retardation have been documented in this series: insufficient purification, low caloric intake, and severe osteodystrophy.

Contribution of experimental studies on the nutritional management of children with chronic renal failure

A few of the many reports of experimental chronic renal failure have been summarized. Anorexia and food selection have been studied in experimental uremia and the findings are comparable with those observed in uraemic children. The optimal dietary protein content for growth is close to the minimal requirement for “optimal” growth. Protein excess leads to growth retardation and renal deterioration in uraemic rats, at least with the commonly used dry diets. The increased water requirement may be more critical for growth than the blood urea level or acidosis, although this requires further investigation. Reduction of the dietary protein by 50% and supplementation with essential amino acids (EAA) results in growth similar to that of the 100% protein diet. There is no growth improvement despite low blood urea levels, but the renal parenchymal is preserved. Supplementation with nitrogen-free analogues is more frequently associated with defective growth; the optimal mixture remains to be defined, and to date, when nutrition is identical, nitrogen-free analogues offer no benefit for renal preservation compared with EAA. Sucrose-rich diets have adverse effects on uraemia. These effects are associated with fructose intolerance and with reduced energy storage in the liver. The precise metabolic alteration remains to be defined.

Renal functional reserve in children with reduced renal mass: study by two dietary periods.

It has been suggested that the “renal functional reserve” (RFR) defined by the rise in glomerular filtration rate (GFR) after a protein load could disappear in patients with severe nephron loss but with a normal GFR. This study compared, in 17 children, inulin clearance (Cin) measured by the plasma inulin plateau at the end of two 14-day randomized periods differing in protein intake: 100% (low protein, LP), or 200% (high protein, HP) of recommended dictary allowances (RDA). Diets were aimed at maintaining food habits and energy intake. Compliance was assessed by records of the last 3–4 days, an interview with the dietician and by urinary nitrogen measurements. Mean actual protein intake was 109% (56%–139%) RDA for the LP period and 220% (163%–319%) RDA for the HP period.Cin did not change in 14 children with GFR below (n=7) or within (n=7) the normal range.Cin was higher in the HP period than in the LP period (+32, 50, 63%) in 3 children who had a 50% (single kidneys) or a 25% (sclerosed glomeruli) nephron loss. Non-responding children had a GFR below 105 ml/min per 1.73 m2. Nephron loss (70% sclerosed glomeruli) was estimated in only 1 child with no RFR. The results suggest that GFR measurement after prolonged dietary stimulation could help in evaluating the severity of nephron loss in children with normal or borderline GFR. The prognostic value of this test has to be confirmed by long-term follow-up.

Comparison of two protein diets in infants with chronic renal failure

Abstract •■ Objective: To compare the effects of two 6-month diet periods in achieving satisfactory growth in infants with chronic renal failure. Diet A consisted of human milk and diet B of a lower quantity of human milk supplemented with essential amino acids (EAA). •■ Design: Randomized trial using a cross-over design. •■ Setting: Nephrology clinic of a major pediatric tertiary referral center in Paris, France. •■ Participants: Sixteen infants (11 male) with an age range from 2 to 5 months. •■ Main outcome measures: Standard anthropometric measures, pertinent laboratory parameters, and serial nutritional intake data. •■ Results: The mean change in length over the study period did not differ between the two diet groups. Growth was better in infants on diet A. The mean weight for statural age showed a trend toward increasing during diet A. Standard laboratory parameters remained stable in both diet groups with the exception of plasma phosphate, which was decreased in infants on both diets, and plasma parathyroid hormone values, which varied in both diet groups. A nasogastric feeding regimen was instituated in 60% of the infants. The mean energy intake did not differ in the two diet groups and was 485 ± 16 kJ/kg body weight (BW) during diet A and 476 ± 7 during diet B. The mean protein intake expressed in g/kg BW was 1.9 during diet A and 1.2 during diet B (milk-EAA). •■ Conclusion: The low-protein diet supplemented with EAA showed neither advantage nor disadvantage over the human milk diet in growth in uremic infants. Human milk is particularly well adapted in uremia. Infants on both diets required phosphorus supplementation.

Zinc bone loss in chronic renal failure and chronic metabolic acidosis

The effects of chronic metabolic acidosis (CMA) on zinc (Zn) bone content and urinary excretion were examined in the presence of normal or reduced renal function together with some aspects of calcium (Ca) metabolism. Four groups of rats were compared. All were fed a 30% protein and 9 mg Zn/100 g diet. Two were uremic (U): The first developed acidosis (UA), which was suppressed in the other (UNA) by NaHCO3 supplement. Two other groups had normal renal function: One was normal (CNA), and the other had NH4Cl in the drinking water and acidosis (CA).Femur total Zn and Ca content was markedly reduced by CMA and was not affected by uremia. Zn urinary excretion was increased by CMA and unaltered by uremia. Ca urinary excretion was markedly reduced in uremic rats, but was enhanced in both acidotic conditions. Urinary Ca and Zn showed a strong correlation in uremic and in control rats. Plasma parathormone and 1,25(OH)2D3 were unchanged by CMA. These data are in agreement with a direct primary effect of CMA on bone in releasing buffers. CMA induces bone resorption and a parallel decrease of mineral bone components, such as Ca and Zn, with little or no role of PTH, 1,25(OH)2D3 and of uremia itself.

Growth, free plasma and muscle amino-acids in uraemic rats fed various low-protein diets

The nutritional effects of low-protein diets are difficult to assess in humans. Normal and uraemic growing rats were therefore fed: a moderately low-protein (12%) reference diet (diet R), two 5% casein diets, one supplemented with essential amino acids (AA) (diet A) and the other with their keto acids (diet K), and a 7% casein diet isonitrogenous with diet K (diet L). Appetite and growth of both uraemic and control rats were identical on diets R and A and were reduced on diets K and L. Stunting was prominent in rats fed diet L and more severe than in those on diet K. Diet K induced marked anorexia in controls. This effect was smaller in uraemic rats, which were all anorectic, regardless of the diet. Plasma essential AA were similar in rats on diets R and A but low in control rats fed diets L and K. In particular, diet K did not improve the branchedchain AA levels although it produced better growth than diet L. Plasma and muscle threonine were surprisingly elevated in rats on the semi-synthetic diets A and K, despite identical or lower consumptions. Regardless of the diet, uraemia resulted in unchanged or increased plasma essential AA, despite reduced appetite and stunting. Uraemia caused a marked rise in some non-essential AA. Muscle essential AA, except for threonine, were essentially unaltered and did not correlate with growth or uraemia.

Highlights Plasma and Muscle Free Amino Acid Alteration in Uremic Children

Simultaneous assessment of plasma and muscle free amino acids (AA) has been performed in children in order to obtain more information about metabolic disturbances presumably related to growth retardation. Plasma and muscle were sampled after an overnight fast and amino acids were measured by ion exchange chromatography with five step lithium buffers.