Growth hormone secretion in response to glucagon stimulation test in healthy middle-aged men / Secreção do hormônio do crescimento em resposta ao teste de estímulo com glucagon em homens saudáveis de meia-idade

OBJECTIVE: To investigate the growth hormone (GH) response to glucagon stimulation test (GST) in a population of healthy men over 50 years old in comparison to insulin tolerance test (ITT), analysis of the spontaneous 24-hour GH profile and insulin-like growth factor 1 (IGF-I). METHODS: 27 healthy men aged between 51 and 65 years were tested. RESULTS: Using non-parametric correlation analysis, a positive correlation between GH peak after GST and mean IGF-I (r = 0.528; p = 0.005) was found, as well with GH peak in 24-hour profile (r = 0.494; p = 0.009). No correlation was found comparing GH peak after ITT with the same parameters. Ten subjects presented GH peak of less than 3.0 μg/L after GST, none confirmed in ITT. CONCLUSIONS: GH peak response to GST was lower than ITT, but it showed a positive correlation with mean IGF-I and also with GH peak in 24-hour profile. However, GST should not be used to differentiate organic growth hormone deficiency (GDH) from the expected decline on GH secretion due to aging.

OBJETIVO: Investigar a resposta do hormônio do crescimento (GH) ao teste de estímulo com glucagon (GST) numa população de homens saudáveis acima dos 50 anos de idade, em comparação ao teste de tolerância à insulina (ITT), além da análise do perfil de secreção espontânea de GH nas 24 horas e fator de crescimento semelhante à insulina (IGF-I) basal. MÉTODOS: 27 homens, com idades entre 51 e 65 anos, foram submetidos aos testes. RESULTADOS: Utilizando análise de correlação não paramétrica, encontrou-se correlação positiva entre o pico de GH pós-GST e a média de IGF-I (r = 0,528; p = 0,005), e também com o pico espontâneo do GH no perfil de 24 horas (r = 0,494; p = 0,009). Não houve correlação do pico de GH pós-ITT com os mesmos parâmetros. Dez indivíduos apresentaram pico de GH após GST inferior a 3,0 μg/L, sem confirmação no ITT. CONCLUSÕES: O pico de GH pós-GST foi menor do que o obtido pós-ITT, porém demonstrou correlação positiva com a média de IGF-I e o pico de GH na secreção espontânea de 24 horas. Entretanto, o GST não demonstrou ser um bom teste para distinguir entre deficiência de hormônio de crescimento (DGH) e somatopausa.

Effects of Growth Hormone Replacement Therapy on Quality of Life in Patients with Somatopause

OBJECTIVE: There is increasing interest in growth hormone (GH) replacement therapy to improve quality of life (QoL) of elderly with age-related decline in GH level (somatopause). The aim of this study was to evaluate the effect of GH replacement on the QoL in patients with somatopause. METHOD: A prospective study of 56 adults with somatopause was conducted. They were replaced with a GH over a 6-month period. QoL was assessed by using three self-rating questionnaires: the Nottingham Health Profile (NHP), the Psychological General Well-Being Index (PGWBI) and theAssessment of Growth Hormone Deficiency in Adults (AGHDA). RESULTS: Significant impairment in QoL as measured by NHP, PGWBI and AGHDA were noted in patients with somatopause compared with age and sex matched normal population (p<0.05). There was significant improvement in QoL after 6-month of GH replacement (p<0.05). CONCLUSION: Six months GH replacement induced an improvement in the QoL of patients with somatopause.

Aging and Hormone Replacement Therapy

Three hormonal systems show decreasing circulating hormone concentrations during normal aging : (1) estrogen(in menopause), and testosterone (in andropause), (2) dehydroepiandrosterone and its sulfate (in adrenopause), and (3) the growth hormone/insulin-like growth factor 1 axis (in somatopause). Throughout the adult life, all physiological functions gradually decline. There is a diminishing capacity for cellular protein synthesis, an decline in immune function, an increase in fat mass, a loss of muscle mass and strength, and a decrease in bone mineral density. Physical changes during aging have been considered physiologic, but there is evidence that some of these changes are related to the decline in the hormonal activity. Various hormonal replacement strategies have been developed, but many of their aspects remain controversial, and increased blood hormone levels in aging individuals to those found during the mid-adult life have not been uniformly proven to be safe and of benefit.

The Predictors of Growth Hormone Secretion after L-dopa Stimulation Test in Adults

BACKGROUND: Twenty four-hour GH secretion reaches a peak in puberty and declines by 14% every decade in adult life. By age 60, most adults have a total 24-hour secretion rate indistinguishable from those of hypopituitary patients with organic lesions in pituitary gland. We performed this study to know about the predictors of GH secretion after L-dopa stimulation test in adults. METHODS: One hundred and ninety eight patients over the age of 45, who visited the menopausal clinic from Oct. 2001 to May 2002, were studied. We compared the peak GH value after the administration of L-dopa 500 mg by gender and age groups. Also, we compared the GH deficiency group to normal by anthropometric and measured variables. RESULTS: The mean of the stimulated GH peak value and the prevalence rate of growth hormone deficiency were greater in women than in men. GH-AUC after L-dopa stimulation correlated well with all measurements of adiposity. In GH deficiency group, the mean values of measured variables about adiposity were greater than normal in statistical significance. Logistic regression test revealed sex and abdominal obesity contributed significantly to predict GH deficiency after L-dopa stimulation test. The odds ratio of GH deficiency were 3.0 in women compared to men with 2.9 in abdominal obesity. CONCLUSION: Gender and adiposity were the predictors of GH deficiency in adults after L-dopa stimulation test rather than age and IGF-1 values.