The regulation of growth in glycogen storage disease type 1

To study endocrine and metabolic variables that affect growth in patients with glycogen storage disease type 1 (GSD-1) receiving standard dietary therapy.

Observational study.

Thirty-eight patients with GSD-1, age range 0.6-32.9 years, were investigated on their usual dietary regimens. Data on height, height velocity in prepubertal children, endocrine and metabolic responses to oral glucose load, 24-h serum cortisol and GH concentration profiles and serum IGF-1 concentrations were collected.

The population studied was shorter than average, with a median height standard deviation score (SDS) of -1.60, but significantly taller than a historical population studied at the same institution that had not received dietary therapy at the time of study. A wide range of height SDS was encountered (-5.28 to 1.21) and a subset still exhibit marked growth failure. Median body mass index (BMI) SDS was 0.72 (range -1.34 to 3.96). Those patients with the greatest BMI SDS had the lowest serum GH concentrations but serum IGF-1 concentrations were within the normal range. Patients with the poorest growth exhibit low serum insulin concentration responses to glucose load, GH insensitivity and higher mean 24-h plasma cortisol levels when compared to those patients who were better grown.

This study shows that overall the growth of this group of patients with glycogen storage disease type 1 has improved compared to that of a historical control group. There remains a subset of this population with poor growth despite therapy. The measured endocrine responses in this subset are similar to those reported for untreated patients. To improve the growth further in these individuals it will be necessary to understand whether this is failure of prescribed therapy or failure to comply with therapy.