Unsuspected renal foci are common in all forms of tuberculosis.
Early radiographic changes are non-specific but later papillary necrosis, ureteral strictures and particularly calcification are suggestive.
Sterile pyuria (i.e. white blood cells in the urine but no pathogen found by standard bacterial culture) is the classic finding.
Special mycobacterial culture of 3 morning urine specimens confirms the diagnosis in the majority.