Bone mineralisation in type 1 glycogen storage disease

Radial bone mineral content (BMC) was measured using single photon absorptiometry in 11 prepubertal children, aged 3.4–12.6 years, with glycogen storage disease type 1 (GSD-1), 2 of whom were receiving granulocyte colony stimulating factor (G-CSF) therapy for chronic neutropenia. Patients were short (median height SD score –1.35, range –3.74 to –0.27), and had reduced BMC Z scores (median 1.79, range –6.35 to +0.27) and radial bone width Z scores (median –0.72, range –2.00 to +0.68). Those receiving G-CSF did not differ significantly from the rest of the group. Generally dietary calcium intake was low and urinary calcium excretion increased. Urinary lactate excretion was high but did not correlate with BMC Z scores. Factors regulating bone metabolism (parathyroid hormone and 25-hydroxy vitamin D concentrations) and markers of bone formation (osteocalcin and skeletal alkaline phosphatase) were not increased implying that there was no compensation for increased bone resorption.Conclusion Patients with GSD-1 may be at increased risk of fracture in later life and require close attention to metabolic control and calcium balance.