Nephrotic syndrome and multiple tubular defects in children: an early sign of focal segmental glomerulosclerosis

Abstract

The nephrotic syndrome is rarely associated with renal tubular defects, and the combination has been reported only in association with advanced renal insufficiency. We report here five children with nephrotic syndrome and multiple tubular defects which evolved when glomular filtration rate ranged between 56 and 90 ml/minute/1.73 m2. The tubular defects were first noted at 3, 4, 4, 7, and 22 months after the onset of the nephrotic syndrome, and renal glycosuria was the first sign in all five children. Glycosuria was intermittent in three patients, constant in two, and ceased with loss of kidney function. Four patients had hyperaminoaciduria and renal tubular acidosis (two of four tested had distal renal tubular acidosis). Three patients had decreased tubular reabsorption of phosphorus and defective maximum concentrating capacity. All five had focal segmental glomerulosclerosis proven by renal biopsy. Over a follow-up period of seven years, all of the children have developed advanced renal insufficiency, four of the five have required dialysis or transplantation within 21 to 72 months after onset, and one has stabilized renal function at 35 ml/minute/1.73 m2. The one patient receiving a kidney transplant has had recurrence of focal segmental glomerulosclerosis in the transplanted kidney and became nephrotic with three subsequent transplants. Our experience suggests that the nephrotic syndrome associated with tubular defects in children forms a subgroup of focal segmental glomerulosclerosis, with rapid progression to renal insufficiency and the potential for recurrence of the lesion in the transplanted kidney.