Effects of rhIGF-1 administration on surrogate markers of bone turnover in adolescents with anorexia nervosa

BackgroundAdolescents with anorexia nervosa (AN) have low bone density and low levels of surrogate markers of bone formation. Low bone density is a consequence of hormonal alterations that include hypogonadism and decreases in IGF-1, a bone trophic factor. Although IGF-1 is key to pubertal bone accretion, and effects have been demonstrated in adults, there are no data regarding the effect of recombinant human (rh) IGF-1 administration in adolescents with AN.ObjectivesWe hypothesized that rhIGF-1 would cause an increase in PINP, a bone formation marker, in girls with AN, without any effect on CTX, a bone resorption marker.Subjects and methodsRhIGF-1 was administered at a dose of 30–40 mcg/k twice daily to 10 consecutive girls with AN 12–18 years old for 7–9 days. Ten age-matched girls with AN were followed without rhIGF-1 for a similar period. IGF-1, PINP and CTX levels were measured.ResultsRhIGF-1 administration caused an increase in IGF-1 from day-1 to day-4/5 (p < 0.0001) and day-1 to day-8/9 (p < 0.0001). Simultaneously, PINP increased from day-1 to day-4/5 (p = 0.004) and day-1 to day-8/9 (p = 0.004), with a smaller increase from day-4/5 to day-8/9 (p = 0.048). CTX levels did not change with rhIGF-1 administration. No changes occurred in IGF-1 or PINP levels in girls not receiving rhIGF-1; however, CTX levels increased significantly (p = 0.01). Percent change in PINP was significantly higher (p = 0.02) and percent change in CTX was significantly lower (p = 0.006) in girls who received rhIGF-1 compared to those who did not receive any intervention. RhIGF-1 was well tolerated without hypoglycemia.ConclusionShort-term administration of rhIGF-1 causes an increase in a surrogate bone formation markers in girls with AN without significant side effects.