Idiopathic prepubertal short stature is associated with low body mass index.

The hypothesis that insufficient body weight is partly responsible for idiopathic short stature was tested by evaluating 79 prepubertal children having idiopathic short stature, classified according to their body mass index (BMI) zs: group 1 BMI zs < or = 0 (m +/- SE, -0.9 +/- 0.1, n = 53) and group 2 BMI zs > 0 (0.6 +/- 0.1, n = 26). Their ages were similar (8.1 +/- 0.3 and 8.4 +/- 0.4 years). The following parameters were significantly lower in group 1 than in group 2: height (-2.5 +/- 0.1 vs. -2.2 +/- 0.1 SD, p < 0.05), height velocity (-1.5 +/- 0.2 vs. -0.9 +/- 0.4 SD, p < 0.05), bone age (bone age retardation 2.3 +/- 0.2 vs. 1.3 +/- 0.4 years, p < 0.005) and plasma insulin-like growth factor 1 (IGF-1, 0.8 +/- 0.1 vs. 1.2 +/- 0.1 U/ml, p < 0.05). The BMI was significantly lower in children with idiopathic short stature (-0.4 +/- 0.1) than in the normal population (zs, p < 0.0002). BMI zs was positively correlated with height (p < 0.005), height velocity (p < 0.05) and plasma IGF-1 (p < 0.01). We conclude that children with idiopathic short stature are leaner than the normal population. An inadequate or insufficient nutritional intake may be partly responsible for idiopathic short stature. The effects of improved intake on the height change are under evaluation.