STATO SECRETORIO DI GH E SOMATOMEDINE CIRCOLANTI NELLA TALASSEMIA: INFLUENZA SU TURNOVER E DENSITA' MINERALE OSSEA

Introduction. Previous data from our group suggested a role for the GH/IGF-I axis in the pathophysiology of osteoporosis in thalassemia (Clin Endocrinol 69:202, 2008). The present study was aimed at evaluating the relationships between circulating somatomedins and bone metabolism and density in a very large series of adult thalassemic patients. Study design. One hundred and thirty-nine patients affected by thalassemia major (mean age 32.3 ± 7.87 years) underwent the following evaluations: assessment of lumbar and femoral BMD by DEXA; measurement of serum osteocalcin and CTx, and urinary NTx; measurement of serum IGF-I and IGF-II; assessment of the GH response to GHRH + arginine. Results. Lumbar osteoporosis and femoral osteoporosis were detected in 54.3% and 58.1% of patients, respectively. IGF-I was low in 86.7% of subjects, whereas none of them displayed low IGF-II. Severe GH deficiency was documented in 27.9% of subjects. In the whole group of patients, IGF-I was positively correlated with GH peak (p < 0.01), osteocalcin (p < 0.0001), CTx (p < 0.0001) and NTx (p < 0.0001), and negatively correlated with age (p < 0.0001), but was not correlated with either lumbar or femoral T-scores. No correlations were found between IGF-II and any of the above parameters, with the exception of age (negative correlation, p < 0,05). The same picture of correlations held true when considering the subset of osteoporotic patients. Conclusions. Our study confirms the high prevalence of both osteoporosis and GH/IGF-I deficiency in thalassemic adults. GH and IGF-I secretory status, but not circulating IGF-II, appears to positively affect bone turnover in this clinical condition. Further, GH secretory status, but not circulatin IGFs, is likely to influence also bone mineralization.