Bone demineralization in adult thalassaemic patients: contribution of GH and IGF-I at different skeletal sites.
OBJECTIVE
GH and IGF-I exert an important role in the control of bone formation, as shown by decreased bone mineral density and increased fracture risk in adult hypopituitary patients untreated for GH deficiency (GHD). Different degrees of bone demineralization are frequently reported in patients affected by beta-thalassaemia. Considering the high prevalence of GHD recently observed by our group among adult thalassaemic patients, we elected to study the possible role of GH-IGF-I abnormalities in the pathogenesis of the osteopenia/osteoporosis of this disease.


METHODS
Sixty-four adult thalassaemic patients (49 with thalassaemia major and 15 with thalassaemia intermedia, 23 men and 41 women, aged 31.4 +/- 6.8 years) were studied.


METHODS
Bone mineral density was assessed by dual energy X-ray absorptiometry at lumbar spine in 62 patients and at proximal femur in 58. All patients underwent GHRH (1 microg/kg as an i.v. bolus) plus arginine (0.5 g/kg as a 30-min i.v. infusion) testing. Severe GHD was defined by GH peaks < 9 microg/l, whereas partial GHD was defined by GH peaks ranging from 9 to 16.5 microg/l. Blood samples for IGF-I measurement were collected.


RESULTS
Lumbar osteoporosis and osteopenia were demonstrated in 46/62 (74.1%) and 14/62 (22.5%) patients, respectively. Femoral osteoporosis and osteopenia were documented in 22/58 (37.9%) and 32/58 (55.1%) patients, respectively. Severe GHD was demonstrated in 16/64 patients (25%), while 11 additional patients (17.1%) displayed partial GHD. IGF-I standard deviation score (SDS) was low, that is, below -1.88, in the majority (54.6%) of patients. Lumbar T-score values were not correlated with either GH peaks or IGF-I SDS values. Femoral T-score values were positively correlated with GH peaks (r = 0.38, P < 0.005) and IGF-I SDS values (r = 0.39, P < 0.005). Multiple regression analysis pointed to both GH peak and IGF-I SDS as predictors of femoral T-score. Furthermore, mean femoral T-score was significantly lower in patients with severe GHD than in those with normal GH secretion (-2.94 +/- 0.25 vs.-2.15 +/- 0.12, P < 0.01).


CONCLUSIONS
This study, while confirming the high prevalence of both osteopenia/osteoporosis and somatotropin-somatomedin deficiency in adult thalassaemic patients, indicates that defective GH secretion and diminished serum IGF-I levels may contribute to femoral demineralization in these patients. Further studies are worth carrying out to evaluate the efficacy of biosynthetic GH administration on bone abnormalities of GH-deficient thalassaemic adults.
Scacchi
Massimo
M
University of Milan, Ospedale San Luca IRCCS, Istituto Auxologico Italiano, Milan, Italy.
Danesi
Leila
L
Cattaneo
Agnese
A
Valassi
Elena
E
Pecori Giraldi
Francesca
F
Argento
Crocetta
C
D'Angelo
Emanuela
E
Mirra
Nadia
N
Carnelli
Vittorio
V
Zanaboni
Laura
L
Tampieri
Benedetta
B
Cappellini
Maria Domenica
MD
Cavagnini
Francesco
F
D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D018488:Bone Demineralization, Pathologic / Q000097:blood / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology; D050276:Hand Bones / Q000000981:diagnostic imaging / Q000473:pathology; D019382:Human Growth Hormone / Q000097:blood / Q000172:deficiency / Q000502:physiology*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000502:physiology*; D008161:Lumbosacral Region / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D055815:Young Adult; D017086:beta-Thalassemia / Q000097:blood / Q000150:complications* / Q000000981:diagnostic imaging / Q000453:epidemiology
D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I