Urinalysis is our most helpful clinical aid in the diagnosis of obscure abdominal maladies. Among the more significant findings are blood, pus, casts and bacteria in urinary tract disease; evidence of biliary pigment in diseases of the hepatic system; polyuria, increase in the specific gravity, and the presence of sugar in many of the pancreatic disturbances.
In a paper on the diagnosis of renal calculus1 I emphasized the importance of the urinary examination and pointed out some of the abdominal conditions that must be borne in mind in making a differential diagnosis. Besides the other kidney diseases I mentioned gallstones, appendicitis, intestinal obstruction, pancreas stone colic, Henoch's purpura and angioneurotic edema. In a doubtful case where the diagnosis lies between ureter or kidney stone and appendicitis, or between urinary tract and hepatic tract diseases, the absence of urinary changes is often as positive an aid in diagnosis as is
HUNNER GL. ACUTE PYELITIS DUE TO ACUTE APPENDICITIS.. JAMA. 1908;L(17):1328-1330. doi:10.1001/jama.1908.25310430012001b