August 28, 2023

Urinary Tract Infections and Kidney Disease

Urinary tract infections (UTIs) are pathological conditions caused by microorganisms that colonize the urinary bladder through the urethra. When the infection is limited to the bladder, it is called “cystitis,” or lower urinary tract infection. When the kidneys are affected, the infection is referred to as “pyelonephritis,” or upper urinary tract infection.

Cystitis and pyelonephritis are more common in women due to anatomical factors. In men, the infection can spread to the prostate gland, causing prostatitis.

UTIs can also be classified as:

  1. a) “complicated” in individuals with:

Metabolic disorders (diabetes, nephrolithiasis)

Congenital abnormalities (vesicoureteral reflux in children)

Neurological conditions (paraplegia, neurogenic bladder)

Immunocompromised states (transplantation, chemotherapy)

Indwelling catheters

  1. b) “uncomplicated” UTIs, which do not have associated anatomical or functional abnormalities.


Cystitis: dysuria, frequency, urgency, suprapubic pain.

Pyelonephritis: In addition to the above, high fever (>38°C), chills, lumbar pain, nausea, vomiting.

The main causative microorganism is Escherichia coli, which is normally found in the gastrointestinal tract.

The clinical presentation, physical examination findings, and laboratory tests contribute to the diagnosis. Urinalysis and urine cultivation are usually sufficient to diagnose “uncomplicated” cystitis.

In the case of pyelonephritis, hospitalization is often required for intravenous antibiotic therapy and concurrent hydration.

“Complicated” urinary tract infections, which occur in the presence of underlying anatomical or functional abnormalities, require additional imaging studies such as:




Computed tomography

Urodynamic studies to assess post-void residual urine volume

“Complicated” urinary tract infections are more strongly associated with chronic kidney disease and require immediate therapeutic intervention by pediatricians, urologists, pathologists, and nephrologists.

Pyelonephritis, especially recurrent urinary tract infections in children, increases the risk of developing renal scars and, consequently, progressive kidney damage that can lead to end-stage renal failure.

Due to the compensatory capacity of the kidneys, the commonly used marker of renal function, blood creatinine, may remain within normal levels despite established and progressing kidney damage. Therefore, close monitoring of this specific patient group is necessary, with additional assessments of renal function such as leukocyturia and creatinine clearance.

It is worth emphasizing that strict regulation of antidiabetic and antihypertensive therapy with appropriate nephroprotective agents is crucial for maintaining stable renal function.

Julia Bakirtzi