Growth Hormone Deficiency in Elderly Patients with Hypothalamo-Pituitary Tumors

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Abstract

In 18 patients with hypothalamo-pituitary diseases aged over 60 years and in 18 sex, age- and BMI-matched healthy subjects, the results of plasma IGF-I and IGF-BP3 levels and the GH response to GHRH+arginine test (GHRH+ATT) were correlated to the results of body composition, serum osteocalcin (OC) and urinary cross-linked N-telopeptides of type I collagen (Ntx) and the bone mineral density (BMD). In 10 patients and 10 controls, the GH response to ITT was also evaluated.

The GH response to GHRH+ATT and ITT was markedly reduced in patients compared to controls (3.1 ± 0.7 vs. 23.2 ± 2.3 μg/L, P < 0.001 and 1.1 ± 0.3 vs. 6.4 ± 0.8 μg/L, P < 0.001), so all patients were classified as GHD, though no significant difference was found in plasma IGF-I and IGF-BP3 levels between the two groups. Body composition analysis revealed a significant increase of fat mass (37.4 ± 2.2 vs. 28.0 ± 1.0%, P < 0.001), a significant decrease of lean mass (62.6 ± 2.2 vs. 72.0 ± 1.0%, P < 0.001) and total body water (45.7 ± 1.5 vs. 52.5 ± 1.1%, P < 0.001) in patients compared to controls. Serum OC levels were lower (1.9 ± 0.1 vs. 4.6 ± 0.4 μg/L, P < 0.001) in patients than in controls, whereas urinary Ntx levels were similar. BMD values in lumbar spine (0.81 ± 0.02 vs. 0.90 ± 0.02 g/cm2, P < 0.01) and femoral neck (0.70 ± 0.02 vs. 0.82 ± 0.02 g/cm2, P < 0.001) were significantly lower in patients than in controls. A significant inverse correlation was found between GHD duration and lumbar spine (r = −0.73, P&1t; 0.001) or femoral neck (r = −0.81, P&1t; 0.001) BMD values and a significant direct correlation was found between GH peak after GHRH+ATT and lumbar BMD (r = 0.69, p = 0.001) in GHD patients.

In conclusion, GHD in patients over 60 yrs aged with a characteristic history of hypothalamus-pituitary pathology is distinct from the physiological decline in GH secretion associated with aging.

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