Increased sodium requirement following early postnatal surgical correction of congenital uropathies in infants.

Serum electrolyte equilibrium and plasma aldosterone concentrations were monitored in 19 infants who had severe obstructive uropathy or grade 5 vesico-ureteral reflux and were undergoing surgical correction in the first 2 months of life. Before surgery high plasma aldosterone levels were observed in 8 patients, but serum sodium and potassium concentrations were normal. Plasma concentrations of aldosterone were elevated in all patients during the week following surgery and 7 patients developed severe hyponatraemia, hyperkalaemia and weight loss despite very high plasma aldosterone concentrations. As a consequence 5 infants were infused with sodium chloride (4 mEq/kg per day) before and for 36 h after surgery; this prevented metabolic imbalance. We conclude that infants undergoing surgical correction of uropathies may require a high sodium intake to maintain electrolyte balance and adequate growth.

Plasma infusion for hemolytic-uremic syndrome in children: results of a multicenter controlled trial.

The results of a controlled trial to ascertain the usefulness of plasma infusion for the treatment of hemolytic-uremic syndrome (HUS) are reported. Criteria for admission were (1) observation within 8 days from first symptoms, (2) dialysis treatment required, and (3) no special treatments and no more than 25 ml blood/kg previously received. Children were subdivided according to age (less than or more than 3 years) and then randomly assigned to treatment with plasma or symptomatic therapy. Thirty-two children ranging in age from 4 months to 6 years entered this study; 17 received plasma (P+ group) and 15 only symptomatic therapy (P- group). The mean follow-up period was 16 months in both groups. Surgical renal biopsy was performed 29 to 49 days after onset in 11 P+ and 11 P- children, and 33 histologic findings were semiquantitatively evaluated. No death occurred in either group. No differences were found in blood pressure, proteinuria, or hematuria at the end of the follow-up period; in no case were severe arteriolar lesions found. There were no significant differences for the scores of the individual histologic measurements; on electron microscopy, no vascular changes were observed in seven children of the P+ group, whereas in five of seven of the P- group, thickening of the lamina rara interna and arteriolar damage were present. The ability of plasma to stimulate prostacyclin (PGI2) production, measured as its stable derivative 6-keto-PGF1 alpha, was within the normal range for all patients. In our patients with predominant glomerular involvement who were treated in a very early phase of HUS, infusions of plasma did not significantly influence the short- and medium-term clinical outcome and were not effective in severe HUS when given later in the course of the disease. A longer follow-up is needed to ascertain whether the presence of endothelial damage, demonstrated by electron microscopy in children who were not given plasma, is of clinical relevance.

Renal function in cystic fibrosis.

The effect of saline extracellular volume expansion (4 ml/min/10 kg b.w. X 60 min) on renal function has been studied in patients with cystic fibrosis (CF) and in normal age-matched controls. Basal values for glomerular filtration rate (GFR), renal plasma flow (RPF), tubular sodium and chloride (Na, Cl) handling were similar in both groups. Saline expansion resulted in an increase in GFR and RPF in the CF patients: 127 +/- 18 ml/min/1.73 sqm BSA to 166 +/- 5; p less than 0.001, but not in the control group: 112 +/- 10 to 120 +/- 20. These hemodynamic changes were associated with increased proximal tubular reabsorption of NaCl in the CF patients whereas controls had reduced NaCl reabsorption. Renin and aldosterone levels suggested that increased NaCl reabsorption in CF patients was not secondary to chronic extracellular volume contraction or salt loss. These results support the hypothesis that the renal tubule is involved in the generalised electrolyte transport disorder exhibited in other epithelial structures. This study also indicated that the regulation of renal hemodynamics is altered in CF. The relationship between the disorder of proximal tubular salt handling and changes in renal hemodynamics is not known, but the observed changes imply a tubulo-glomerular feedback mechanism.

Prediction of the progression of renal failure in adult and in pediatric patients with malignant focal glomerulosclerosis.

A retrospective analysis of the progression of renal failure was performed in 6 children and 5 adults with idiopathic nephrotic syndrome unresponsive to steroids and immunosuppressants and with histological findings of focal glomerulosclerosis. We analyzed the linear regression of Ccr and of their logarithmic transformation vs time (months) starting from the time when the first abnormal value was observed (t = 0). The regression analysis was performed at three different times, when Ccr was: 30-20, 20-25 and 10-15 ml/min/1.73 sqm. Extrapolation of each of these lines on the x axis predicted when renal function would be zero. The difference in months, between the predicted and actual time of starting dialysis was prediction error. "r" values were always elevated and statistically significant for both linear and logarithmic regression; there was a large intersubject variability in the rate of loss of renal function but the mean prediction error at various levels of Ccr was within limits clinically acceptable. Moreover its magnitude did not significantly decrease by prolonging the time of observation. This indicates that in this disease the decay of Ccr enters a track which proceeds linearly or logarithmically after the onset of renal failure and no major deviation from the predicted line is to be expected. The good predictability in our study may be attributed to the fact that our patients were homogeneous for a number of factors which may be relevant to progression of the disease. It confirms the view supported by Gretz et al. [1983] that there is a need for stratification of patients in large cohort studies on the predictability of loss of renal function.

Renal tubular acidosis in a case of Shwachman's syndrome.

We describe metabolic acidosis in a 15-month-old girl with clinical features of Shwachman's syndrome. Renal function tests indicated that the patient had type 1 renal tubular acidosis. Based on our findings and other reports of renal tubular dysfunction in patients with Shwachman's syndrome, we conclude that it is important to look for a possible renal tubular defect in this syndrome.

Intraplatelet serotonin (I5HT) in children with the hemolytic uremic syndrome.

I5HT levels were investigated in 14 children with Hemolytic Uremic Syndrome (HUS). Low levels of I5HT were demonstrated in all the children studied during the early phase of the disease, indicating reversible platelet aggregation and recirculation of degranulated platelets. Three months after the onset of HUS, only 2 children with a pathological picture of cortical necrosis and a mild degree of chronic renal failure had low I5HT levels. On the contrary, normal I5HT levels were present in the other children completely recovered from HUS and with a renal biopsy picture of thrombotic microangiopathy with predominant glomerular involvement. We conclude that normal values of I5HT, after the acute stage of HUS, are a good index of complete recovery from the disease. Further observations are required to assess the prognostic value of low I5HT levels in children with chronic renal failure secondary to HUS.