In the sequence for suspected FSGS, which test is used to confirm the diagnosis?

• A. Renal biopsy
• B. Urinalysis
• C. Blood pressure
• D. Serum creatinine

Answer: (A)

The key idea is that confirming FSGS requires histologic proof from kidney tissue. A renal biopsy provides the definitive diagnosis because it shows the characteristic pattern: focal (in some glomeruli) and segmental (part of the glomerulus) sclerosis with hyalinosis on light microscopy. Electron microscopy often reveals podocyte foot-process effacement, while immunofluorescence is usually nonspecific or negative for immune complex deposits. Other tests, like urinalysis or measurements of blood pressure or serum creatinine, can indicate kidney involvement or function but cannot definitively distinguish FSGS from other nephrotic-glomerular diseases. Thus, tissue diagnosis from a renal biopsy is the best confirmatory test.