<prompt> An 8-year-old child suffering from recurrent attacks of polyurea since childhood presents to the paediatrics OPD. On examination the child is short statured vitals and B.P. are normal. Serum Creatinine 6 mg, HCO3 16 meq, Na 134, K 4.2 On USG bilateral small kidneys are seen. Diagnosis is -Reflux NephropathyNephronophthisisPolycystic kidney diseaseMedullary cystic kidney disease  <response>: The lab investigations and symptoms of the child suggest Juvenile nephronophthisis.Juvenile nephronophthisis It is the most common genetic cause of end-stage renal disease renal failure in childhood and adolescence.It is an autosomal recessive disease.The patients present before the age of 20 years.The pt. presents withInability to conserve sodium because of defect of tubules leading to polyuria and polydipsia Polyurea is resistant to vasopressinAnaemiaGrowth retardation growth retardation, malaise pallor are secondary to anaemia which is attributed to a def. of erythropoietin production by failing kidneysNo hypertension As nephronophthisis is salt-losing nephropathyProteinuria and hematuria usually are absentSonography shows b1 small kidneys with multiple cysts only in the medulla cysts may only be seen if they are large enough. They are rarely visible early in diseaseJuvenile nephronophthisis is usually associated with many extra-renal conditions, one of which is hepatic fibrosis, which explains the high level of alkaline phosphatase in this patient.Radiographic featuresSmall kidneys Loss of corticomedullary junction Multiple cysts About other optionsMedullary cystic diseasePatient with medullary cystic disease presents with similar features as Juvenile Nephronophthisis but it can be differentiated by -The absence of Growth RetardationAge of presentation is 3rd or 4th Decade.Hypertension may occur in JN, hypertension is not seen.In polycystic kidney disease, there is bilateral enlargement of the kidney.In reflux Nephropathy the kidneys do not decrease in size and there will be a history of frequent urinary tract infections. 