Urinary System Involvement in Children With Cystic Fibrosis: A Single-Center Retrospective Cohort

Cystic fibrosis (CF) is a multisystem genetic disorder. While pulmonary and gastrointestinal manifestations are well recognized, urinary system involvement in children with CF remains limited.

We retrospectively evaluated children with CF who had at least one urine sample available for analysis. Demographic and clinical characteristics, routine urinalysis findings, spot urine biochemical measurements (available in a subset of children), and abdominal ultrasonography results were reviewed. Urinary abnormalities were defined as the presence of calcium oxalate crystalluria and/or renal calculi detected on ultrasonography.

A total of 41 children with CF (23 males, 56.1%) were included, with a median age of 6.0 years (range 0.5-17). Calcium oxalate crystalluria was detected in 13 children (31.7%), and renal calculi were identified in 8 of those who underwent ultrasonography (19.5%). Most renal calculi were small (median size 3 mm) and located in the lower poles of the kidneys, and none of the children required surgical intervention. Estimated glomerular filtration rate was preserved in most patients, and no demographic or routinely assessed biochemical parameters were independently associated with urinary abnormalities.

Urinary abnormalities, particularly crystalluria and nephrolithiasis, appear to be relatively common in children with CF, often in the absence of overt renal dysfunction. Periodic assessment of routine urinalysis and urine microscopy may facilitate early identification of urinary abnormalities and guide further evaluation when clinically indicated. Prospective studies incorporating comprehensive metabolic stone assessments are warranted to clarify the clinical significance of these findings.