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 / Somatotrophic status is a major determinant of thyroid hormone(TH) action in growth hormone deficient(GHD) children: implicactions for levothyroxine therapy in central hypothyroidism

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Previous issue date: 2007 / 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. / BV UNIFESP: Teses e dissertações

Links & Downloads

1. 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.
2. http://repositorio.unifesp.br/handle/11600/23455
3. Publico-23455.pdf

Tags

Hipotireoidismo

Metabolismo energético

Tiroxina/uso terapêutico

Additional Fields

Identifer	oai:union.ndltd.org:IBICT/oai:repositorio.unifesp.br:11600/23455
Date	January 2007
Creators	Martins, Manoel Ricardo Alves [UNIFESP]
Contributors	Universidade Federal de São Paulo (UNIFESP), Abucham, Julio [UNIFESP]
Publisher	Universidade Federal de São Paulo (UNIFESP)
Source Sets	IBICT Brazilian ETDs
Language	Portuguese
Detected Language	English
Type	info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis
Format	40 f.
Source	reponame:Repositório Institucional da UNIFESP, instname:Universidade Federal de São Paulo, instacron:UNIFESP
Rights	info:eu-repo/semantics/openAccess