The kidneys are the primary way of excretion of bone seeking radiopharmaceuticals and normally are well seen on bone scintigrams. In up to 15% of bone scintigrams urinary tract abnormalities are detected as incidental findings. 
- BILATERAL DIFFUSE ABNORMALITIES
- UNILATERAL OR BILATERAL FOCAL ABNORMALITIES
- ABNORMAL SIZE, SHAPE OR POSITION
Diffuse increased renal uptake is usually caused by dehydration, but can also be seen with hypercalcemia, sickle cell anemia, nephrocalcinosis , and after administration of antineoplastic agents or gentamicin. Focal increased accumulation of activity is often noted in normal or obstructed collecting systems or rarely in primary or metastatic renal neoplasms. It may also be seen after radiation therapy. Focal areas of decreased renal uptake are generally seen with space-occupying lesions such as abscesses, cysts, primary, and metastatic neoplasms.
