Which lab test can help identify a potential streptococcal infection in acute glomerulonephritis?

A throat culture is the most appropriate lab test for identifying a potential streptococcal infection in the context of acute glomerulonephritis. This condition is often associated with infections caused by Group A Streptococcus, particularly following pharyngeal infections like strep throat. The throat culture allows for the direct identification of streptococcal bacteria, confirming whether a recent infection could be linked to the glomerulonephritis.

While urinalysis can reveal abnormalities in the urine that may suggest kidney involvement due to infections, it does not specifically identify the presence of streptococcal bacteria. A blood glucose test is primarily used to monitor diabetes and not relevant to diagnosing streptococcal infections. Additionally, a chest X-ray is utilized to evaluate lung conditions and would not assist in diagnosing a streptococcal infection or its role in glomerulonephritis. Thus, the throat culture stands out as the targeted test to potentially confirm the underlying infection related to the kidney condition.