Comparative analysis of nephrolithiasis in otherwise healthy versus medically complex gastrostomy fed children

Purpose: The purpose was to compare nephrolithiasis in healthy versus medically complex gastrostomy fed children. Materials and methods: Children with nephrolithiasis with and without gastrostomy were identified by database searches from 1999 to 2009. Gastrostomy fed stone formers (GSF) were compared to an age-matched cohort of non-gastrostomy-fed stone formers (NGSF) for demographic and clinical data. Results: 16 neurologically impaired GSF (10M:6F), mean age 10.4 years (range 1.7-17.5 years), were compared to 32 matched neurologically intact NGSF. Compared to NGSF, GSF had significantly higher urine pH (6.93 vs 6.23, p = 0.001) and larger stones (14.5 vs 6.9 mm, p = 0.02) more commonly composed of calcium phosphate (7/11, 64% vs 3/28, 11%, p = 0.002). 15/16 (94%) of GSF were immobile while 0% of NGSF were immobile. GSF had lower l-spine bone density Z-scores (-3.02 vs -1, p = 0.002) but an equal rate of hypercalciuria (2/7, 29% vs 7/24, 29%, p = NS). Contributing lithogenic factors in 8/16 (50%) GSF included urinary tract infection (UTI) (5), lithogenic medications (2), and xanthinuria (1). Conclusions: Stone disease in GSF is multifactorial, and half of our study group had an identifiable risk factor for nephrolithiasis. A recurring pattern of alkaline urine and calcium phosphate stone formation was evident. GSF did not have higher rates of hypercalciuria despite chronic immobilization and markedly lower bone density. An awareness of the potential risk factors identified is mandatory for this vulnerable population.