<prompt> Acute pyelonephritis and uncomplicated UTI may be differentiated by all of the following, except:WBC castConcentrating defectOrganisms in excess of 100,000 cfumlAntibody to Tomm Horsfall protein  <response>: Although acute pyelonephritis may be associated with organisms in excess of 100,000CFUml, this test cannot be used to localize the infection to the kidneys as such high counts are also seen in uncomplicated UTIs. All other tests mentioned are used to localize the infections to the kidney. Ref: Harrisons Principles of Internal Medicine, 16th Edition, Page 1717; Diagnosis of Genitourinary Disease By Resnick and Older, 2nd Edition, Pages 275-77 