Which finding in urinalysis may suggest acute kidney damage?

The presence of bacterial casts in urinalysis is indicative of acute kidney damage, particularly in the context of acute tubular necrosis or other forms of kidney injury associated with infection or inflammation. Bacterial casts form when bacteria invade the renal tubules and are subsequently imprinted in the casts that are shed into the urine. This finding suggests that there is an active process occurring in the kidneys, typically involving damage to the tubular cells, which can be due to various factors such as toxins, infections, or ischemia.

In contrast, the presence of glucose in urine may indicate conditions like diabetes or renal glycosuria but is not specific to kidney damage. High specific gravity can indicate concentrated urine, often seen in dehydration or conditions that lead to increased solute load, but it does not specifically suggest acute kidney damage. The absence of crystals may simply denote normal urine composition and is not indicative of any type of kidney injury. Therefore, the presence of bacterial casts serves as a more definitive marker of acute kidney damage in the context of urinalysis.