Hypothalamic involvement and insufficient sex steroid supplementation are associated with low bone mineral density in women with childhood onset craniopharyngioma

Abstract

Data on bone mineral density (BMD) are lacking in adults with childhood onset (CO)-craniopharyngioma (CP) with hypothalamic damage from the tumor. In patients with CO GH deficiency, BMD increases during GH treatment. The aims were to evaluate BMD in adults with CO-CPs on complete hormone replacement, including long-term GH and to evaluate the impact of hypothalamic damage on these measures. BMD (dual-energy X-ray absorptiometry), markers of bone turn over, physical activity and calcium intake were assessed in 39 CO-CP adults (20 women), with a median age of 28 (17-57) years, in comparison with matched population controls. Late puberty induction was recorded in both genders, but reduced androgen levels in females only. Only CP women had lower BMD (P=0.03) at L2-L4, and reduced Z-scores at femoral neck (P=0.004) and L2-L4 (P=0.004). Both genders had increased serum leptin levels (P=0.001), which significantly correlated negatively with BMD at L2-L4 (P=0.003; r=-0.5) and 45% of CP women had Z-score levels ≤-2.0 s.d. Furthermore, 75% of those with a Z-score ≤-2.0 s.d. had hypothalamic involvement by the tumor. Calcium intake (P=0.008) and physical activity (P=0.007) levels were reduced in CP men only. Levels of ostecalcin and crossLaps were increased in CP men only. Despite continuous GH therapy, low BMD was recorded in CO-CP females. Insufficient estrogen and androgen supplementation during adolescence was the main cause, but hypothalamic involvement with consequent leptin resistance was also strongly associated with low BMD in both genders.