This is a chronic interstitial nephritis associated with vesico-ureteric reflux (VUR, usually congenital) in early life. There is also a close association with recurrent urinary tract infections , and sometimes there are other urinary tract or other congenital abnormalities such as incomplete growth of the kidney - renal hypoplasia.
Normally the oblique entrance of the ureter through the bladder wall causes ureteric occlusion during bladder contraction. In VUR there is a structural abnormality of the intra-mural ureter allowing reflux of urine from the bladder to the kidney. Chronic Interstitial Nephritis becomes established leading to further renal deterioration. By an uncertain mechanism, interstitial nephritis may cause focal scars and initiate a slowly progressive renal deterioration.
Often asymptomatic. May present with hypertension, proteinuria reflecting renal damage; or with associated UTIs. Reflux itself sometimes causes loin pain during micturition but this is rarely a significant problem.
Diagnosis is confirmed by demonstration of focal renal scars (cross-sectional imaging or isotope renogram; ultrasound less reliable for this); will also reveal other abnormalities, e.g. obstruction. Urine culture necessary to show infection. Assess renal function, proteinuria etc. in usual way.
Associated UTIs should be managed in the usual way. Correct obstruction. There is no consistent benefit from procedures to correct reflux. If there is significant renal damage (proteinuria, hypertension, renal function), aggressive control of blood pressure is important. Other aspects as for CRF of other causes.