Certified Nephrology Nurse Certification (CNN) Practice Exam 2025 - Free Nephrology Nursing Practice Questions and Study Guide

The most useful laboratory test for diagnosing glomerulonephritis is urinalysis showing hematuria and proteinuria. Glomerulonephritis is characterized by inflammation of the glomeruli, which affects the kidneys' ability to filter blood efficiently. A urinalysis is a key diagnostic tool because it can reveal specific abnormalities associated with this condition.

In glomerulonephritis, hematuria (the presence of blood in the urine) is often due to the breakdown of glomerular filtration barriers, allowing blood cells to leak into urine. Additionally, proteinuria (the presence of excess protein in the urine) is also a common finding, as the damaged glomeruli can no longer effectively filter proteins from the blood.

Other diagnostic options, such as imaging studies (like X-rays or CT scans) and blood tests (like BUN), can provide some information about kidney structure or function but are not definitive for identifying glomerulonephritis. These tests may rule out other conditions or provide supplementary information, but urinalysis is specifically indicative of the type of damage and dysfunction that occurs in glomerulonephritis. Thus, the urinalysis is critical for confirming the diagnosis and guiding further management.