Subclinical defects in renal regulation of acid base balance in children with recurrent urinary tract infections

Effect on renal function of essential fatty acid supplementation in cystic fibrosis

Changes in renal hemodynamics, sodium homeostasis, renal acidifying capacity, and aldosterone excretion were studied before and after long-term intravenous essential fatty acid supplementation for a period of 3 years in 11 patients with cystic fibrosis. The mean (+/- SD) glomerular filtration rate was high at the start of the study (133 +/- 18 ml/min/1.73 m2 body surface area) and decreased significantly (p less than 0.05) to within normal values after 1 year of essential fatty acid supplementation. The urinary elimination of an oral sodium load initially was very low (3.6 +/- 2.5 mmol/hr/1.73 m2 body surface area vs control subjects' values of 7.9 +/- 2.0; p less than 0.001) and increased during treatment but was not normalized (p less than 0.05 vs control subjects' values). Free water clearance and distal tubular sodium delivery, which were significantly decreased before treatment (p less than 0.01 and p less than 0.001 vs control subjects' values, respectively) did not increase significantly. The mean urinary aldosterone excretion did not significantly differ from that in control subjects before and after treatment. The acidifying capacity was disturbed, indicating a low renal bicarbonate threshold, and was changed during treatment in only 2 of 10 patients. These data indicate that essential fatty acid deficiency may contribute to the renal disturbances in cystic fibrosis.

Renal dysfunction in recurrent urinary tract infections in childhood

One hundred children aged 1.5-19.5 years, with recurrent urinary tract infections, at least one of which was febrile (pyelonephritis, PN), were investigated by means of inulin and para-aminohippurate (PAH) clearance tests for the evaluation of glomerular filtration rate (GFR), effective renal plasma flow, and concentrating and diluting capacities. Renal function data were collated with the clinical history and radiological findings. GFR and PAH clearance were found to be reduced compared with controls. Patients whose first PN was diagnosed before the age of 3--particularly those with a history of three or more PN infections--showed the lowest values for GFR and PAH clearance. Furthermore, parenchymally reduced kidneys were found most frequently in this group of patients. Concentrating capacity was decreased in some patients, but a low concentrating capacity did not reveal patients with reduced GFRs. Diluting capacity evaluated as minimal urine osmolality was normal, but was reduced when evaluated as free water clearance in some patients with reduced values for GFR.

The syndrome of hypertension and hyperkalaemia with normal glomerular function (Gordon's syndrome). A pathophysiological study

A 14-year-old boy with the syndrome of hypertension and hyperkalaemia with normal glomerular filtration rate (Gordon's syndrome) is described. The patient's clinical symptoms consisted of periodic paralysis, slight metabolic acidosis of the proximal type and hypercalciuria. Prostaglandin excretion was normal. Infusion of atrial natriuretic peptide had no effect on electrolyte excretion or glomerular function although a normal increase in cyclic guanosine monophosphate was demonstrated in plasma and urine. This lack of sensitivity to atrial natriuretic peptide offers a new pathophysiological concept in this syndrome. Treatment with hydrochlorothiazide was successful in this case.

Renal magnesium wasting in two families with autosomal dominant inheritance

Hypomagnesemia due to isolated renal magnesium loss was demonstrated in two unrelated families with autosomal dominant mode of inheritance. Magnesium infusions performed in two patients showed not only a reduced renal magnesium threshold but also a lowered renal tubular maximum for magnesium. All members of both families who presented with hypomagnesemia had also a lowered excretion of calcium in the urine, presumably as a consequence of increased reabsorption in Henle's loop.