O estado somatotrófico é um determinante importante da ação do hormônio tiroideano em crianças com deficiência de hormônio de crescimento: implicações para a terapia com levotiroxina no hipotiroidismo central

O estado somatotrófico é um determinante importante da ação do hormônio tiroideano em crianças com deficiência de hormônio de crescimento: implicações para a terapia com levotiroxina no hipotiroidismo central

Alternative title Somatotrophic status is a major determinant of thyroid hormone(TH) action in growth hormone deficient(GHD) children: implicactions for levothyroxine therapy in central hypothyroidism
Author Martins, Manoel Ricardo Alves Autor UNIFESP Google Scholar
Advisor Abucham, Julio Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Graduate program Medicina (Endocrinologia clínica) - EPM
Abstract Context: The biological significance of GH-induced changes in serum TH concentrations is unknown. It has been suggested that serum FT4 should be targeted at the high normal range during GH replacement. Objective: To evaluate the effects of GH replacement on thyroxine biological effects. Hypothesis: If GH modulates thyroxine biological effects, serum FT4 should be targeted accordingly. Design/Setting: Observational (Study 1) and interventional (Studies 2- 3)/Outpatient. Patients: 32 GHD patients (13 off GH; 22 on L-thyroxine). Interventions: Study 2: Levothyroxine to increase FT4 (>1.0ng/dL). Study 3: GH administration or withdrawal. Main outcome measures: FT4, TT3, myocardial isovolumic contraction time (ICT) and resting energy expenditure (REE). Results: Study 1: OFF GH and ON GH groups had similar FT4, but OFF GH showed lower TT3 (P<0.01) and REE (P=0.02), higher ICT (P<0.05) than ON GH and controls. On GH, ICT and REE correlated only with TT3 (r=-0.48, r=0.58, P<0.05). Off GH, ICT correlated only with FT4 (P<0.01). Study 2: Off GH, levothyroxine intervention increased FT4 (P=0.005), TT3 (P=0.012), decreased ICT (P=0.006), increased REE (P=0.013); ICT and FT4 changes correlated (r=-0.72, P=0.06). On GH, levothyroxine increased FT4 (P=0.0002), TT3 (P=0.014), REE (P=0.10), decreased ICT (P=0.049); REE and TT3 changes correlated (r=0.60, P=0.05). Study 3: GH decreased FT4, increased TT3, decreased ICT, increased REE (P<0.05). REE correlated (P<0.05) with IGF-I (r=0.57), TT3 (r=0.64). ICT correlated only with TT3 (r=-0.47). Conclusions: GH replacement improves the biological effects of thyroxine. Serum FT4 should be targeted at the high normal range in GHD patients only off GH replacement.
Keywords Hipotireoidismo
Metabolismo energético
Tiroxina/uso terapêutico
Hormônio do crescimento/uso terapêutico
Language Portuguese
Date 2007
Published in MARTINS, Manoel Ricardo Alves. O estado somatotrófico é um determinante importante da ação do hormônio tiroideano em crianças com deficiência de hormônio de crescimento: implicações para a terapia com levotiroxina no hipotiroidismo central. 2007. 40 f. 40 f. Tese (Doutorado em Ciências) – Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, 2007.
Publisher Universidade Federal de São Paulo (UNIFESP)
Extent 40 f.
Access rights Open access Open Access
Type Thesis
URI http://repositorio.unifesp.br/handle/11600/23455

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