<prompt> A boy is suffering from acute pyelonephritis. Most specific urinary finding will be-W.B.C. castsLeucocyte esterase testNitrite testBacteria in gram stain  <response>: Answer is A W.B.C Presence of W.B.0 cast in urine of patients with suspected pyelonephritis is considered pathognomic. Leucocyte casts W.B. C cast are present in the urine of some patients with Pylonephritis and the detection of these is considered pathognomic 