Final answer:
The presence of WBC casts in urinary sediment is a specific indicator that pyuria has a renal origin, pointing towards a potential upper urinary tract infection.
Step-by-step explanation:
The presence of white blood cells (WBCs) in urinary sediment can suggest a variety of conditions, but most commonly it indicates a urinary tract infection (UTI). Specifically, the correct statement about WBCs in urinary sediment among the options provided is that WBC casts indicate that pyuria is of renal, rather than lower urinary, origin.
This is because the formation of WBC casts occurs within the kidney tubules and provides evidence that the infection or inflammation is occurring at a renal level rather than just in the lower urinary tract. It is not true that "glitter cells" are a sign of renal disease, as they can be present with infection.
Bacteriuria without WBCs does not always indicate a lower urinary tract infection, as WBCs may not have yet appeared in the sediment. It is also incorrect to state that WBCs other than polymorphonuclear cells (PMNs) are not found in the urinary sediment, because lymphocytes and other WBCs can be present.