Growth dependence on insulin-like growth factor-1 during the ketogenic diet

To examine the influence of the ketogenic diet (KD) on linear growth and insulin-like growth factor I (IGF-I) levels in children with pharmacotherapy-resistant epilepsy.

A prospective study was designed to evaluate growth, serum IGF-I levels, blood beta-hydroxybutyric acid (beta-OHB), and seizure frequency before and during KD in 22 children (median age 5.5 years). Growth was assessed by measurements of weight, height, body mass index (BMI), and height velocity. Standard deviation scores (SDS) were calculated for all measured parameters as well as for serum IGF-I to eliminate the influence of age- and sex-related differences among patients.

Fourteen of the 22 patients responded to the KD. Weight, height, BMI, and height velocity decreased significantly during the KD. We found that the KD had profound influence on growth and IGF-I levels. No correlation was found between seizure response and growth alterations. Height velocity correlated negatively with beta-OHB during the KD. The slope of the regression of height velocity against IGF-I decreased significantly during the KD.

Height velocity was most affected in those with pronounced ketosis, which implies that, in clinical practice, the level of ketosis should be related to outcomes in seizure response and growth. Our data indicate that growth disturbances and the decreased sensitivity of growth to similar IGF-I levels during KD are independent of seizure reduction. The metabolic status induced by KD may be the mechanism underlying both alterations of linear growth and seizure reduction.