Stone forming risk factors in patients with type Ia glycogen storage disease.

PURPOSE: Patients with type Ia glycogen storage disease have an increased recurrent nephrolithiasis rate. We identified stone forming risk factors in patients with type Ia glycogen storage disease vs those in stone formers without the disease. MATERIALS AND METHODS: Patients with type Ia glycogen storage disease were prospectively enrolled from our metabolic clinic. Patient 24-hour urine parameters were compared to those in age and gender matched stone forming controls. RESULTS: We collected 24-hour urine samples from 13 patients with type Ia glycogen storage disease. Average +/- SD age was 27.0 +/- 13.0 years and 6 patients (46%) were male. Compared to age and gender matched hypocitraturic, stone forming controls patients had profound hypocitraturia (urinary citrate 70 vs 344 mg daily, p = 0.009). When comparing creatinine adjusted urinary values, patients had profound hypocitraturia (0.119 vs 0.291 mg/mg creatinine, p = 0.005) and higher oxalate (0.026 vs 0.021 mg/mg creatinine, p = 0.038) vs other stone formers. CONCLUSIONS: Patients with type Ia glycogen storage disease have profound hypocitraturia, as evidenced by 24-hour urine collections, even compared to other stone formers. This may be related to a recurrent nephrolithiasis rate greater than in the overall population. These findings may be used to support different treatment modalities, timing and/or doses to prevent urinary lithiasis in patients with type Ia glycogen storage disease.