Growth hormone - insulin-like growth factor-I axis and bone mineral density in adults with thalassemia major

Bone disease and short stature are frequent clinical features of patients with beta-thalassaemia major. Dysfunction of the GH-IGF-1 axis has been described in many thalassemics children and adolescents with short stature and reduced growth velocity. Assessment of the GH-IGF-1 axis in short adults with TM after attainment of final height may be required to select those who are candidates for replacement therapy and to prevent the development of bone disease. The aim of our study was to investigate GH secretion in adult thalassemic patients in relation to their bone mineral density (BMD) and serum ferritin concentrations.

We performed clonidine stimulation test in 30 thalassemic patients (18 males, 12 females) with a mean age of 31.5± 7.2 years. The cut-off level for GH response was set at 7ug/l, according to the literature. Serum ferritin, IGF-I, liver enzymes, alkaline phosphatase (ALP) and type 1 Collagen Carboxy Telopeptide (CCT1) were also determined.

We diagnosed GH deficiency (GHD) in 12 patients (40%) and IGF-I deficiency (IGF-I SDS <-2) was diagnosed in 20 patients (67%). Adult patients with TM had significantly decreased IGF-I concentrations and bone mineral density (BMD) at the femur neck and lumbar spine compared to normal controls. Thalassemic patients with GHD and IGF-I deficiency had significantly lower BMD T score at the lumbar spine compared to patients with normal GH and IGF-I levels. Thalassemic patients had higher serum CCT1 concentrations compared to normal controls. Peak GH levels were correlated significantly with IGF- I concentrations and IGF-I levels were correlated significantly with the height SDS (HtSDS) of thalassemic patients. Neither GH peak nor IGF-I concentrations were correlated to serum ferritin concentrations.

We conclude that GH status should be tested in adult thalassemic patients especially those with short stature and/or decreased BMD. Clonidine test appears to be effective and safe in adults with TM. If the diagnosis of adult GHD is established, GH treatment may be considered for possible improvement of bone mineral density and heart function in patients with TM.