Kidney Pain on Both Sides? Understanding Pyelonephritis Symptoms and What They Mean
Experiencing pain in both sides of the lower back could be a sign of a deeper health issue, particularly involving the kidneys. One common condition linked to bilateral flank discomfort is pyelonephritis—an infection that affects the renal pelvis and kidney tissue. While some people may assume kidney pain only occurs on one side, it's entirely possible for both kidneys to be involved, especially in certain forms of this infection. This article explores the symptoms, types, and diagnostic clues associated with pyelonephritis, helping you better understand when to seek medical attention.
What Is Pyelonephritis?
Pyelonephritis is a type of urinary tract infection (UTI) that has traveled up to the kidneys, causing inflammation and potential damage if left untreated. It can develop suddenly or persist over time, leading to two primary classifications: acute and chronic pyelonephritis. Both types can cause significant discomfort and systemic symptoms, but they differ in duration, severity, and long-term effects on kidney function.
Acute Pyelonephritis: Sudden Onset With Intense Symptoms
This form of kidney infection strikes quickly and is often severe. Patients typically experience high fever, chills, and shaking spells, which may resemble flu-like illness but are rooted in bacterial invasion of the upper urinary tract. The hallmark symptom is unilateral or bilateral flank pain—a deep, dull ache in the sides of the lower back where the kidneys are located.
Another telltale sign is tenderness upon percussion (knocking) over the kidney area during a physical exam, known as costovertebral angle tenderness. Alongside pain, individuals often report urinary urgency, frequent urination, painful urination, and sometimes visible blood in the urine (gross hematuria).
Diagnostic tests such as urinalysis commonly reveal white blood cells (pyuria), bacteria (bacteriuria), and occasionally protein or red blood cells. A definitive diagnosis is made through a clean-catch midstream urine culture, which identifies the specific pathogen—most often Escherichia coli—and guides antibiotic treatment.
Chronic Pyelonephritis: A Long-Term Threat to Kidney Health
Unlike its acute counterpart, chronic pyelonephritis develops gradually and may result from repeated or unresolved kidney infections. During flare-ups, patients might again experience fever, dysuria, and increased urinary frequency. However, what sets this condition apart is the presence of progressive kidney damage over time.
Many individuals report persistent dull aching or pressure in both flanks, along with changes in urinary patterns such as nocturia (frequent nighttime urination) and overall increased urine output. As kidney function declines, signs of renal insufficiency begin to emerge—these include nausea, poor appetite, fatigue, weakness, and pallor due to anemia.
How Doctors Diagnose Chronic Kidney Involvement
To confirm chronic pyelonephritis, healthcare providers rely on imaging and functional testing. Radiological studies, such as ultrasound, CT scans, or intravenous pyelograms (IVP), often show structural abnormalities like scarring, uneven kidney surfaces, or reduced kidney size.
In addition, laboratory assessments of tubular function reveal key markers: low urine specific gravity, decreased urine osmolality, and elevated levels of enzymes like NAG (N-acetyl-β-D-glucosaminidase). These findings indicate impaired concentrating ability and ongoing tubular injury—critical indicators of chronic kidney disease stemming from recurrent infection.
When to See a Doctor
If you're experiencing unexplained back pain on one or both sides, especially accompanied by fever or urinary symptoms, it's essential to consult a healthcare professional promptly. Early diagnosis and treatment can prevent complications such as sepsis, permanent kidney damage, or hypertension related to renal scarring.
Staying hydrated, practicing good urinary hygiene, and addressing UTIs early are proactive steps to reduce your risk. For those with recurrent infections, further evaluation for underlying causes—such as urinary obstructions, vesicoureteral reflux, or immune deficiencies—may be necessary.
Understanding the signs of pyelonephritis empowers you to take control of your kidney health. Whether the pain is on one side or both, don't ignore persistent symptoms—your kidneys play a vital role in filtering waste and maintaining overall wellness.