An analysis of acid-labile subunit (ALS) levels in children with short stature born with normal weight.

Introduction: The acid-labile subunit (ALS) is a protein best known for its function in stabilising the insulin like growth factor-1/2-insulin-like growth factor-1 binding protein 3/5 (IGF-1/2-IGFBP3/5) binary complex by creating the ternary complex and in consequence regulating the biological activity of IGF-1. The aim of the study was to assess ALS concentrations in a chosen population of children with short stature taking into account their clinical diagnosis.

Material and methods: A total of 109 prepubertal children were involved in the study - 85 children in the study group and 24 in controls. In all the children IGF-1, IGFBP3, and ALS were measured. The study group was divided according to diagnosis into groups: growth hormone deficiency (GHD), constitutional delay of growth and puberty (CDGP), idiopathic short stature (ISS), and familial short stature (FSS).

Results: In the control group the ALS concentration ranged from 4.81 to 13.66 μg/mL. In the whole study group the ALS concentration ranged from 2.73 to 15.81 μg/mL. The difference between both groups was statistically significant (p < 0.0001, R = 0.39). A strong, statistically significant correlation between ALS levels and age was observed, but only in the study group (p < 0.0001, r = 0.59). The ALS standard deviation score (SDS) was not significantly different between the control and CDGP children (p = 0.0644). The ALS concentration was significantly lower in children with short stature. There was, however, no difference between the subgroups of the study group.

Conclusion: There was no significant difference in ALS SDS between the control group and children with constitutional delay of growth and development. The usefulness of ALS in routine short stature diagnostics is uncertain, but it might play a role in the diagnosis of children with ISS and CDGP in the future.