Login to Access Video or Poster Abstract: MP95-12
Sources of Funding: None

Introduction

Patients with neurologically derived musculoskeletal deficiencies (NDMD), like spinal cord injury and spina bifida, are high risk for chronic complicated urolithiasis. Recent studies suggest that stone etiology in this population has shifted from purely infectious to mixed infectious/metabolic. We assess a cohort of NDMD patients for metabolic lithogenic risk factors, trends across etiology of NDMD, as well as trends across primary stone type.

Methods

We conducted a retrospective cohort study of NDMD patients presenting to our dedicated &[prime]stone clinic&[prime] from 2000-2015. Patients with chemical stone and 24-hour urine analysis were included. Demographics, neurological deficiency, bladder management strategy, urine cultures, 24-hour urine, and stone composition were reviewed.

Results

Seventy eight patients with NDMD and nephrolithiasis were identified. Of these, 26 had both chemical stone and 24 hour urine analysis. Positive urine cultures prior to treatment were present in 77%. Eighty-five percent of these cultures were positive for urea splitting organisms. The most common stone type categorized by primary composition was carbonate apatite (53.8%) followed by mixed apatite/oxalate (19.2%). When categorized by primary etiology, 61.5% were pure pH dependent (presumed to be infectious), 27% mixed pH dependent/metabolic, and 11.5% pure metabolic. Urinary citrate was significantly lower in patients with carbonate apatite, or pH dependent, calculi. Those with primarily calcium oxalate stones were significantly more likely to be obese (p=0.003), with a mean body mass index of 37. When stratified by gender, males were more likely to have hyperoxaluria. There was a trend toward positive cultures for urea splitting organisms and carbonate apatite stones in catheterized patients. Otherwise, there were no statistically significant differences in 24-hour urine parameters when stratified by gender, neurological deficiency, or bladder management strategy. _x000D_

Conclusions

Among NDMD patients, metabolic factors may play a more significant role in stone formation than previously believed. There is still a high incidence of carbonate apatite stones, which could be attributed to bacteriuria and elevated pH. In addition to this, obesity, low volumes, low citrate, and elevated oxalate suggest a metabolic etiology. Identifying metabolic risk factors in NDMD patients is challenging but important; as it may significantly impact stone recurrence and the need for repeat surgery.

Funding

None