A 53-year-old man with gout for many years usually experiences 4-5 attacks a year. He treats each flare with an over-the-counter nonsteroidal anti-inflammatory drug (NSAID), but is not taking any medications for gout prophylaxis.On physical examination, there are no active joints presently, but he does have some tophaceous deposits on his left hand. As part of his complete evaluation, screening for renal complications of gout is performed. Which of the following findings is most likely compatible with chronic gouty nephropathy?

Diminished concentrating ability and proteinuria occur even when the glomerular filtration rate is near normal in gouty nephropathy. The severity of renal involvement correlates with the duration and magnitude of serum uric acid elevation. Uric acid and monosodium urate deposit in the renal parenchyma. These deposits can cause intrarenal obstruction and elicit an inflammatory response as well. Hypertension, nephrolithiasis, and pyelonephritis can also contribute to the nephropathy of gout. Nephrotic syndrome, acute kidney injury, and ATN are not characteristics of chronic gouty nephropathy, though patients with gout may be at risk for these disorders for other reasons.