Background Osteoporosis is frequently observed in patients with glycogen storage disease (GSD) type 1. An abnormal metabolic and endocrine environment as well as delayed puberty seems to explain the presence of osteoporosis in GSD patients.
Methods 19 patients (12 GSD1a; 7 GSD1b) were enrolled in the study. Biochemical parameters of mineral metabolism and pituitary and gonadic hormones have been analysed. Bone mineral density has been evaluated by dual energy x ray absorptiometry (DEXA) and by quantitative ultrasound of proximal phalanges (QUS).
Results Serum calcium and phosphorus levels and alkaline phosphatase were normal in all patients. Plasmatic and urinary magnesium levels were increased in both GSD1a and GSD1b patients. Parathormone levels were reduced and vitamin D levels were normal in all patients; calcitonin levels were increased in 1/12 GSD1a and 3/7 GSD1b patients; osteocalcin levels were increased in 3/7 GSD1b patients and reduced in 3/12 GSD1a patients. Hypercalciuria was observed in 3/12 GSD1a patients and none of GSD1b patients, whereas high hydroxyproline excretion was observed in 3/12 GSD1a and 5/7 GSD1b patients. The Z-score of DEXA was below −2.5 DS in 3/7 GSD1b patients; in two different GSD1b patients the Z-score of QUS was below −2.5 DS. In patients with abnormal DEXA and QUS Z-scores hydroxyproline excretion was increased. In GSD1b patients IGF1 levels were related to DEXA values.
Conclusions The results of this study underline the presence of impaired mineral metabolism in both GSD1a and GSD1b patients. According to our data QUS may represent a useful tool to assess bone mineral status in GSD1 patients.