The effects of recombinant GH doses (10 micrograms/kg.day, 3 times a week for 6 months) lower than those previously used in the treatment of GH-deficient adults (GHDA) on body composition, bone mineral content, and heart structure and function were investigated in seven (six males and one female, aged 25-27 yr) GHDA. They were studied before treatment, after treatment, and 6 months after stopping therapy, and findings were compared with those for 20 sex-, age-, and body mass index-matched healthy controls.
Before treatment, GHDA showed a significant reduction in insulin-like growth factor-I levels, an increase in bioimpedance and fat mass percentage, a reduction of bone density at both distal and proximal sites, a decrease in bone Gla- protein and procollagen III levels, and significant cardiac impairment supported by a reduction of left ventricular mass index and left ventricular systolic function with decreased fractional shortening and rate-adjusted mean velocity of circumferential fiber shortening. GH treatment normalized insulin-like growth factor-I levels, body composition and echocardiographic findings, but not bone density. Six months after stopping therapy, all parameters investigated returned to the pretreatment conditions.
Our results suggest that prolonged GH deficiency induces alterations in body composition and bone metabolism and density, and impairment of cardiac structure and function in adult life. GH replacement therapy for 6 months, despite the low doses used by us, is able to improve all previously impaired biochemical and clinical features, except for bone density. This improvement disappears 6 months after the withdrawal of therapy.