A nurse is reviewing the laboratory results of an adolescent who has chronic glomerulonephritis. Which of the following findings should the nurse expect?

The correct answer is D: BUN 50 mg/dL (elevated). In chronic glomerulonephritis, there is impaired kidney function leading to decreased filtration and retention of waste products like blood urea nitrogen (BUN), causing elevated levels. Absence of proteinuria (choice A) is incorrect because glomerulonephritis typically presents with proteinuria. Serum phosphorus (choice B) and serum potassium (choice C) within the expected reference range are incorrect as electrolyte imbalances are common in glomerulonephritis.