Intravenous urogram (IVU) is primarily used to assess the urinary tract, including the kidneys, ureters, and bladder. One major indication for performing an IVU is calculus disease, which involves the presence of kidney stones or urinary calculi. These stones can cause obstruction, pain, and infection, making it essential to visualize their location and size through imaging. Other conditions listed, such as hypertension, diabetes, and asthma, are not direct indications for IVU, as they do not primarily affect the urinary system.