Final answer:
A superscan in bone scintigraphy shows increased bone uptake activity and absent or greatly reduced kidney/bladder uptake, suggestive of advanced skeletal conditions.
Step-by-step explanation:
The so-called superscan of bone scintigraphy has increased bone uptake activity and absent or greatly reduced kidneys/bladder uptake. This situation often indicates advanced skeletal involvement, as seen with metastatic bone disease or other conditions such as hyperparathyroidism. In a superscan, the radiopharmaceutical uptake in the bones is so high due to increased metabolic or reparative activity that it diminishes the appearance of the kidneys and bladder in the scan, which normally excrete the tracer.