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Previous issue date: 2013-06-28 / Importance: Obesity has become a major public health problem due to its growing prevalence in recent decades and its comorbidities. Many studies have related abdominal fat to metabolic abnormalities and increased risk of cardiovascular diseases in adults, but there are few studies that have examined these questions in adolescents. Atherosclerotic disease is the major cause of morbidity and mortality around the world. Atherosclerosis has been demonstrated to begin in childhood and measurement of carotid artery intima-media thickness (cIMT) by ultrasonography (US) can be used to evaluate cardiovascular risk in this population. Whether the thickness of arterial wall increases with body mass index (BMI) is still a matter of debate. Objective: The purpose of this study was to assess the association between ultrasound measurements of abdominal fat and automated US measurements of cIMT with anthropometric and laboratory data in a group of adolescents in order to identify potential markers that may be used to control the development of risk factors for cardiovascular disease in adolescents. Patients and Methods: Forty-five patients aged 10 to 17 years were enrolled in this study voluntarily. The subjects were evaluated in a pediatric outpatient clinic at either the Instituto da Crian?a da Universidade de S?o Paulo in S?o Paulo or the Hospital S?o Lucas da Pontif?cia Universidade Cat?lica do Rio Grande do Sul in Porto Alegre. Adolescents were classified as obese or eutrophic according to their body mass index z-score for Brazilian children and adolescents. We determined waist circumference, waist-to-height ratio and conicity index from all subjects. We obtained blood samples from all subjects after 12 hours of fasting to measure glycemia, triglyceride, total cholesterol, HDL-cholesterol, LDL-cholesterol, insulin, and apolipoprotein B levels. We calculated the patients HOMA-IR index, a mathematical model that quantifies insulin resistance based on the formula: HOMA-IR = fasting Insulin (μUI/mL) x fasting glucose (mmol/L) / 22.5. All patients received an ultrasound assessment of subcutaneous tissue, pre-peritoneal fat, and intra-abdominal fat and all of them received an US assessment of the common carotid artery intima-media thickness. Results: Ultrasonographic measures of abdominal fat were found to be associated with anthropometric measurements, glucose level, insulin level, and HOMA-IR (except glucose and maximal pre-peritoneal fat). In our multivariate analysis, body mass index z-score, conicity index, and HOMA-IR remained independently associated with the subjects sum of fat. Only minimal subcutaneous fat associated independently with HOMA-IR. In relation to the vascular US evaluation, cIMT was not associated with sex or BMI z-score. However, cIMT on both the right and the left sides was found to associate positively with height. Additionally, cIMT on the right side was found to associate positively with waist circumference and HOMA-IR, and negatively with apolipoprotein B levels. In our multivariate analysis, only height remained independently associated with cIMT (right and left). Conclusions: Subcutaneous fat may be more useful than visceral fat as a marker for insulin resistance in adolescents. In the US measurements of both cIMT, only height was independently associated with this automated method. Further studies should be conducted on a prospective basis in order to identify potential markers that could be used to prevent the development and progression of cardiovascular pathology in pediatric patients. / Import?ncia: A obesidade tornou-se um importante problema de sa?de p?blica devido ? sua preval?ncia crescente nas ?ltimas d?cadas e suas comorbidades. Muitos estudos t?m relacionado gordura abdominal com anormalidades metab?licas e com aumento do risco de doen?as cardiovasculares em adultos, mas poucos estudos examinaram essas quest?es em adolescentes. A doen?a ateroscler?tica ? a principal causa de morbidade e mortalidade em todo o mundo. A aterosclerose inicia-se na inf?ncia e a medida ultrassonogr?fica da espessura m?dio-intimal carot?dea (EMIC) por ultrassonografia (US) pode ser usada para avaliar o risco cardiovascular nessa popula??o. Ainda ? uma quest?o de debate se a espessura da parede arterial aumenta com o ?ndice de massa corporal (IMC). Objetivo: O objetivo deste estudo foi avaliar a associa??o entre as medidas ultrassonogr?ficas de gordura abdominal e as medidas ultrassonogr?ficas automatizadas da EMIC, com dados antropom?tricos e laboratoriais em um grupo de adolescentes, a fim de identificar potenciais marcadores que possam ser usados para controlar o desenvolvimento de fatores de risco para doen?a cardiovascular. Pacientes e m?todos: Quarenta e cinco pacientes com idade entre 10 e 17 anos foram inclu?dos neste estudo de forma volunt?ria. Os indiv?duos foram avaliados ambulatorialmente no Instituto da Crian?a da Universidade de S?o Paulo, em S?o Paulo, e no Hospital S?o Lucas, da Pontif?cia Universidade Cat?lica do Rio Grande do Sul, em Porto Alegre. Os adolescentes foram classificados como obesos ou eutr?ficos, de acordo com seu escore-z de IMC (adaptado para as crian?as e adolescentes brasileiros). Determinou-se a circunfer?ncia abdominal (CA), a raz?o entre a circunfer?ncia abdominal e estatura (CA:A) e o ?ndice de conicidade (IC) de todos os pacientes. Amostras de sangue foram obtidas de todos os indiv?duos ap?s 12 horas de jejum para medi??o da glicemia, triglicer?deos (TG), colesterol total (COL), HDL-colesterol (HDL), LDL-colesterol (LDL), insulina e apolipoprote?na B (apoB). O ?ndice HOMA-IR (Homeostasis Model Assessment), modelo matem?tico que quantifica a resist?ncia ? insulina por meio da f?rmula: HOMA-IR = Insulina jejum (μUI/mL) x Glicose jejum (mmol/L) / 22,5, foi calculado, e todos os pacientes receberam uma avalia??o ultrassonogr?fica das gorduras (subcut?nea, pr?-peritoneal e intra-abdominal) e da EMIC. Resultados: As medidas ultrassonogr?ficas de gordura abdominal associaram-se com as medidas antropom?tricas, a glicose, a insulina e o HOMA-IR (exceto glicose e gordura pr?-peritoneal m?xima). Na an?lise multivariada, o escore-z do IMC, o IC e o HOMA-IR permaneceram associados de forma independente com o somat?rio de gordura dos pacientes. Apenas a gordura subcut?nea m?nima associou-se de forma independente com o HOMA-IR. Em rela??o ? avalia??o ultrassonogr?fica vascular, a EMIC n?o foi associada com o sexo ou com o escore-z do IMC. No entanto, EMIC de ambos os lados associou-se positivamente com a altura. Al?m disso, EMIC direita associou-se positivamente com CA e com o HOMA-IR e negativamente com os n?veis de apoB. Na an?lise multivariada, apenas a altura permaneceu independentemente associada com EMIC (direita e esquerda). Conclus?es: A gordura subcut?nea pode ser mais ?til do que a gordura visceral como um marcador para a resist?ncia ? insulina em adolescentes. Na aferi??o ultrassonogr?fica da espessura m?dio-intimal carot?dea, apenas a altura foi independentemente associada com esse m?todo automatizado. Estudos adicionais devem ser conduzidos de forma prospectiva, a fim de identificar potenciais marcadores que possam ser utilizados para evitar o desenvolvimento e a progress?o de patologias cardiovasculares em pacientes pedi?tricos.
| Identifer | oai:union.ndltd.org:IBICT/oai:tede2.pucrs.br:tede/1422 |
| Date | 28 June 2013 |
| Creators | Lazaretti, Arthur Silva |
| Contributors | Baldisserotto, Matteo |
| Publisher | Pontif?cia Universidade Cat?lica do Rio Grande do Sul, Programa de P?s-Gradua??o em Medicina/Pediatria e Sa?de da Crian?a, PUCRS, BR, Faculdade de Medicina |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da PUC_RS, instname:Pontifícia Universidade Católica do Rio Grande do Sul, instacron:PUC_RS |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 3098206005268432148, 500, 600, -8624664729441623247 |
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