How to Identify Nephritis Through Urinalysis: Symptoms, Diagnosis, and Key Indicators
Diagnosing nephritis often begins with a thorough evaluation of clinical history and urinalysis results. Acute glomerulonephritis, in particular, typically follows a recent streptococcal infection—such as strep throat or skin infection—and presents with sudden onset symptoms. One of the most telling signs is abnormal findings in a routine urine test, including hematuria (blood in urine), proteinuria (excess protein), and the presence of urinary casts, which indicate kidney inflammation.
Recognizing Early Warning Signs of Kidney Inflammation
In children, especially between the ages of 5 and 12, a prior history of upper respiratory infection can serve as a red flag. For instance, consider a 10-year-old boy who had a cold about a week earlier and now presents with dark, tea-colored urine—a classic sign of hematuria. A urinalysis reveals 3+ red blood cells and over 200 red blood cells per high-power field under the microscope. These findings strongly suggest glomerular damage.
Alongside urinary abnormalities, additional systemic symptoms such as facial or limb swelling (edema), elevated blood pressure (e.g., 140/90 mmHg), headaches, abdominal discomfort, and fatigue further support the diagnosis. Hypertension in this context may result from fluid retention and impaired kidney function, both common in acute glomerulonephritis.
Clinical Testing and Laboratory Confirmation
Blood Tests That Support the Diagnosis
To confirm acute post-streptococcal glomerulonephritis, healthcare providers rely on specific blood markers. A positive anti-streptolysin O (ASO) titer indicates a recent Group A streptococcal infection. Additionally, a significant drop in complement C3 levels helps differentiate this condition from other forms of kidney disease, such as lupus nephritis, where complement levels may also be low but follow a different pattern.
Other lab tests may include serum creatinine and estimated glomerular filtration rate (eGFR) to assess overall kidney function. In most cases of acute glomerulonephritis, renal impairment is temporary, and function gradually improves with proper management.
Treatment Approach and Prognosis
Once diagnosed, patients are usually advised to rest in bed during the acute phase, especially if hypertension or edema is present. Treatment focuses on managing symptoms—using antihypertensive medications if needed, restricting salt intake, and monitoring fluid balance. Antibiotics may be prescribed if an active streptococcal infection is still present, although they do not reverse kidney damage once it has occurred.
The good news is that the incidence of acute glomerulonephritis has declined over the years, likely due to earlier detection and prompt use of antibiotics for streptococcal infections. Most pediatric cases have an excellent prognosis, with full recovery expected within weeks to months.
Why Early Detection Matters
Parents and caregivers should be vigilant about changes in a child's urine color, energy levels, or facial swelling after a sore throat or skin infection. Early medical evaluation can prevent complications such as acute kidney injury or hypertensive encephalopathy. Routine urinalysis remains a simple yet powerful tool in identifying kidney involvement at an early stage.
In summary, while urinalysis plays a central role in suspecting nephritis, a combination of clinical symptoms, serological tests, and patient history provides the full picture needed for accurate diagnosis and effective treatment planning.