The areas of scarring are associated with tubulointerstitial fibrosis overlying deformed calyxes of the collecting system. Glomeruli show only minor changes until there has been considerable parenchymal damage. There is often a poor relation between the severity of a patient's symptoms, the degree of reflux, and the number of infections the patient has experienced. Presenting features can include such signs of urinary tract infection as back or flank pain, fever, and dysuria. Hypertension, when present, is often associated with high levels of renin, which may derive from the segmental areas of scarred parenchyma.
Patients often have a urinary concentrating defect, leading to nocturia and polyuria.
Proteinuria is mild unless the patient has developed advanced renal insufficiency, with glomerular hyperfiltration, and focal segmental glomerulosclerosis. Diagnosis of reflux nephropathy is based on evidence of the reflux of urine and characteristic parenchymal and clinical findings. Reflux is demonstrated with a voiding cystourethrogram, either with contrast agents or by radionuclide scanning. Because urinary tract infection may be associated with reflux, it is best to wait several weeks after treating a urinary tract infection before trying to diagnose reflux nephropathy. Many persons with such mild reflux undergo spontaneous remission with time.