22-31: Renal Manifestations of Tuberculosis

Renal tuberculosis usually results from hematogenous spread and is an underdiagnosed entity. It is estimated that up to 20% of patients with extrapulmonary tuberculosis have urogenital involvement, of which the kidney is most commonly affected. Clinically, the classic renal manifestation of tuberculosis is the presence of microscopic pyuria with a sterile urine culture—or “sterile pyuria.” More often, other bacteria are also present, and microscopic hematuria may coexist. Urine cultures are the gold standard for diagnosis; three to six first morning midstream specimens should be performed to improve sensitivity. Although not usually needed to confirm the diagnosis, kidney biopsy will show granulomatous inflammation. Papillary necrosis and cavitation of the renal parenchyma occur less frequently, as do ureteral strictures and calcifications. Adequate drug therapy can result in resolution of renal involvement.