RESUMO
Deviations from normal growth are a major part of Pediatric Endocrinology. The principal post-natal growth promoting hormones are pituitary growth hormone (GH) and insulin-like growth factor-I (IGF-I). The GH-IGF-I axis has many links and portals, the secrets of which have been disclosed in recent years by scientific advances (genetic and biochemical technologies). In this article, we describe the players in the GH axis, the auxological indications for performing GH evaluation tests, enumerate the most frequently used tests and discuss the laboratory tests which help to define the pathological entities along the GH axis. Emphasis is put on the limitations of methods used, lack of standards, norms and the possible errors in diagnosis and treatment indications that may evolve. As both hGH and IGF-I immunoassay measurements represent cornerstones in the diagnosis and monitoring of the different etiological entities presenting with short stature, clinicians must have an insight into the variability and limitations of these analytical techniques. Interpretation of biochemical results without proper reference data and without knowledge of the assay-inherent characteristics inevitably leads to misdiagnosis, unnecessary further testing and treatment and imposes a burden on the child, family and the health care system.
Assuntos
Proteínas de Transporte/análise , Hormônio do Crescimento Humano/análise , Hormônio do Crescimento Humano/deficiência , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/análise , Fator de Crescimento Insulin-Like I/análise , Determinação da Idade pelo Esqueleto , Antropometria , Estatura , Pré-Escolar , Testes Diagnósticos de Rotina/métodos , Grelina/genética , Crescimento , Hormônio Liberador de Hormônio do Crescimento/genética , Hormônio do Crescimento Humano/genética , Humanos , Masculino , Receptores de Neuropeptídeos/genética , Receptores de Hormônios Reguladores de Hormônio Hipofisário/genética , Receptores da Somatotropina/genética , Sensibilidade e Especificidade , Somatostatina/genéticaRESUMO
BACKGROUND & AIMS: An imbalance of energy intake and energy expenditure leads to obesity. However, little detailed information of energy expenditure and physical activity patterns in obese subjects is available. Therefore, we assessed total energy expenditure (TEE) with its components resting energy expenditure (REE) and activity thermogenesis (AT) and the patterns of physical activity in non-obese and in subjects with different degrees of obesity. METHODS: TEE and activity pattern were assessed with the SenseWear™ armband in 78 subjects (46 ± 12 years; 28 with normal weight/overweight, 13 each with obesity I° and II°, and 24 with obesity III°). In addition, REE was measured by indirect calorimetry and AT was calculated. RESULTS: Although TEE (and REE) increased with increasing weight category from 2567 (1437) kcal/d in non-obese subjects to 3033 (1931) kcal/d in subjects with obesity III° (p=0.016, p<0.001, respectively) body weight adjusted TEE decreased from 33.1 to 22.1 kcal/kg/d (p<0.001). This was mainly due to decreased body weight adjusted AT (11.3-5.8 kcal/kg/d, p<0.001). AT consisted almost completely of non-exercise AT. In particular, for obese subjects exercise-related AT was negligible. CONCLUSIONS: Higher degrees of obesity are associated with decreased body weight adjusted AT. These differences have to be considered for therapeutic strategies.