Obesidade e esteatose grave: a importância da avaliação bioquímica e escores / Obesity and severe steatosis: the importance of biochemical exams and scores

RESUMO - RACIONAL: A doença hepática gordurosa não-alcoólica já é considerada um problema de saúde pública, principalmente em pacientes com obesidade severa. OBJETIVOS: O objetivo do presente estudo foi investigar os diferentes escores de bioquímiosa disponíveis e determinar qual deles poderia servir melhor como uma ferramenta de avaliação da NAFLD em uma população de obesos. MÉTODOS: Este é um estudo transversal de pacientes obesos. Todos os pacientes foram avaliados com parâmetros laboratoriais séricos 1 semana antes da biópsia e todos os pacientes foram submetidos a biópsia hepática intra-operatória, durante a cirurgia bariátrica. RESULTADOS: Cento e quarenta e três pacientes obesos foram incluídos. Apenas APRI (0,65; IC 95%: 0,55 a 0,8) e HOMA-IR (0,7; IC 95%: 0,58 a 0,82) mostraram capacidade significativa de predição de esteatose grave. HSI, NALFDS, ALS / AST e FIB-4 não foram capazes de prever corretamente esteatose grave na biópsia hepática. APRI mostrou alta especificidade (82%) e baixa sensibilidade (54%). Em contraste, o HOMA-IR apresentou alta sensibilidade (84%) e baixa especificidade (48%). CONCLUSÃO: O NALFDS, FIB-4, AST / ALT e HSI não têm utilidade para avaliação de esteatose grave em pacientes com obesidade severa. Diabetes e avaliação bioquímica relacionada à resistência à insulina, como o HOMA-IR, podem ser empregados como boas ferramentas de rastreamento para esteatose grave em tais pacientes. O escore APRI é a ferramenta diagnóstica bioquímica mais específica para esteatose em pacientes com obesidade severa e pode ser empregado, por equipes médicas, para auxiliar na indicação de cirurgia bariátrica ou metabólica.

ABSTRACT - INTRODUCTION: Nonalcoholic fatty liver disease (NAFLD) is considered a public health problem, mainly in severely obese patients. OBJECTIVE: The aim of the present study was to investigate different biochemical-based scores available and determine which one could best serve as an NAFLD predicting tool in a severely obese population. METHODS: This was a cross-sectional study involving severely obese patients. All patients were evaluated with serum laboratory parameters for 1 week before biopsy, and all patients were treated with intraoperative liver biopsy, during bariatric surgery. RESULTS: A total of 143 severely obese patients were included. The median body mass index (BMI) was 48 kg/m2 (35-65). Diabetes mellitus was present in 36%, and steatosis was present in 93% (severe steatosis in 20%). Only aspartate transaminase (AST) to platelet ratio index (APRI=0.65 (95% CI: 0.55-0.8) and homeostatic model assessment for insulin resistance (HOMA-IR=0.7 (95% CI: 0.58-0.82) showed significant capacity for the prediction of severe steatosis. Hepatic steatosis index (HSI), NAFLD fibrosis score (NAFLDS), alanine aminotransferase (ALT)/AST, and fibrosis-4 (FIB-4) were not able to correctly predict severe steatosis on liver biopsy. APRI showed high specificity of 82% and low sensitivity of 54%. In contrast, HOMA-IR showed high sensitivity of 84% and low specificity of 48%. CONCLUSIONS: NAFLDS, FIB-4, AST/ALT, and HSI have no utility for the evaluation of severe steatosis in severely obese patients. Diabetes and insulin-resistance-related biochemical assessments, such as HOMA-IR, can be used as good screening tools for severe steatosis in these patients. APRI score is the most specific biochemical diagnostic tool for steatosis in severely obese patients and can help clinicians to decide the need for bariatric or metabolic surgery.

Lactate can be a marker of metabolic syndrome in severe obesity? / Lactato pode ser marcador da síndrome metabólica na obesidade grave?

ABSTRACT Background: In the last decades, numerous studies have confirmed the importance of lactate - by-product to the nutrient signal of the intracellular redox state - to regulatory functions in energy metabolism. Aim: To evaluate changes in blood lactate in patients with severe obesity and its correlation with body composition and metabolic profile. Methods: Twenty-four people with severe obesity (BMI=40 kg/m2) were evaluated in a prospective case-control study before and six months after Roux-in-Y gastric bypass. The blood lactate, total cholesterol, and fractions, C-reactive protein and HOMA-IR were analyzed after 12 h fasting. Body mass composition was evaluated by bioelectrical impedance and respiratory quotient was measured by indirect calorimetry. Results: The initial lactate level was 2.5±1.1 mmol/l and returned to normal level (1.9±3.6 mmol/l, p=0.0018) after surgery. This reduction was positively correlated with a decrease in BMI (p=0.0001), % free fat mass (p=0,001), % fat mass (p=0.001) and HOMA-IR (p=0.01). There was normalization of lactatemia in 70% of patients. There was no correlation between lactatemia and C-reactive protein. Conclusions: There was a significant improvement of metabolic parameters, normalization of blood lactate, fat mass loss, although these individuals remained with a high BMI.

RESUMO Racional: Nas últimas décadas, inúmeros estudos confirmam a importância do lactato - subproduto ao sinal de nutrientes do estado redox intracelular - às funções reguladoras do metabolismo energético. Objetivo: Avaliar alterações no lactato sanguíneo em pacientes com obesidade grave e sua correlação com a composição corporal e o perfil metabólico. Métodos: Vinte e quatro pacientes com obesidade grave (IMC=40 kg/m2) foram avaliadas em um estudo prospectivo antes e após seis meses do bypass gástrico em Y-de-Roux. O lactato sanguíneo, colesterol total e frações, proteína C-reativa e HOMA-IR foram analisados após 12h de jejum. A composição corporal foi avaliada por bioimpedância elétrica e o quociente respiratório por calorimetria indireta. Resultados: O nível inicial de lactato foi de 2,5±1,1 mmol/l e retornou ao nível normal após a operação (1,9±3,6 mmol/l, p=0,0018). Essa redução foi correlacionada positivamente com a diminuição do IMC (p=0,0001), % de massa livre de gordura (p=0,001) e % de massa de gordura (p=0,001) e HOMA-IR (p=0,01). Houve normalização da lactatemia em 70% dos pacientes. Não houve correlação entre lactatemia e proteína C-reativa. Conclusões: Houve melhora significativa dos parâmetros metabólicos e normalização da lactatemia, perda de massa gorda, embora esses indivíduos permanecessem com IMC elevado.

C-peptide level as predictor of type 2 diabetes remission and body composition changes in non-diabetic and diabetic patients after Roux-en-Y gastric bypass

OBJECTIVES: Several predictors of type 2 diabetes mellitus (T2DM) remission after metabolic surgery have been proposed and used to develop predictive scores. These scores may not be reproducible in diverse geographic regions with different baseline characteristics. This study aimed to identify predictive factors associated with T2DM remission after Roux-en-Y gastric bypass (RYGB) in patients with severe obesity. We hypothesized that the body composition alterations induced by bariatric surgery could also contribute to diabetes remission. METHODS: We retrospectively evaluated 100 patients with severe obesity and T2DM who underwent RYGB between 2014 and 2016 for preoperative factors (age, diabetes duration, insulin use, HbA1c, C-peptide plasma level, and basal insulinemia) to identify predictors of T2DM remission (glycemia<126 mg/dL and/or HbA1c<6.5%) at 3 years postoperatively. The potential preoperative predictors were prospectively applied to 20 other patients with obesity and T2DM who underwent RYGB for validation. In addition, 81 patients with severe obesity (33 with T2DM) underwent body composition evaluations by bioelectrical impedance analysis (InBody 770®) 1 year after RYGB for comparison of body composition changes between patients with and those without T2DM. RESULTS: The retrospective analysis identified only a C-peptide level >3 ng/dL as a positive predictor of 3-year postoperative diabetes remission, which was validated in the prospective phase. There was a significant difference in the postoperative body composition changes between non-diabetic and diabetic patients only in trunk mass. CONCLUSION: Preoperative C-peptide levels can be useful for predicting T2DM remission after RYGB. Trunk mass is the most important difference in postoperative body composition changes between non-diabetic and diabetic patients.

Changes in the intestinal microbiota of superobese patients after bariatric surgery

OBJECTIVES: The gut microbiota is associated with obesity and weight loss after bariatric surgery and has been related to its changing pattern. Exactly how the bacterial population affects weight loss and the results of surgery remain controversial. This study aimed to evaluate the intestinal microbiota of superobese patients before and after gastric bypass surgery (RYGB). METHOD: DNA fragments for the microbiota obtained from stool samples collected from nine superobese patients before and after bariatric surgery were sequenced using Ion Torrent. RESULTS: We observed that with a mean follow-up of 15 months, patients achieved 55.9% excess weight loss (EWL). A significant population reduction in the Proteobacteria phylum (11 to 2%, p=0.0025) was observed after surgery, while no difference was seen in Firmicutes and Bacteroidetes. Further analyses performed with two specific individuals with divergent clinical outcomes showed a change in the pattern between them, with a significant increase in Firmicutes and a decrease in Bacteroidetes in the patient with less weight loss (%EWL 50.79 vs. 61.85). CONCLUSIONS: RYGB affects the microbiota of superobese patients, with a significant reduction in Proteobacteria in patients with different weight loss, showing that different bacteria may contribute to the process.

Very low-calorie diet in candidates for bariatric surgery: change in body composition during rapid weight loss

OBJECTIVE: To analyze the changes in the body composition of morbidly obese patients induced by a very low-calorie diet. METHODS: We evaluated 120 patients selected from a university hospital. Body composition was assessed before and after the diet provided during hospitalization, and changes in weight, body mass index, and neck, waist and hip circumferences were analyzed. Bioimpedance was used to obtain body fat and fat-free mass values. The data were categorized by gender, age, body mass index and diabetes diagnosis. RESULTS: The patients consumed the diet for 8 days. They presented a 5% weight loss (without significant difference among groups), which represented an 85% reduction in body fat. All changes in body circumference were statistically significant. There was greater weight loss and a greater reduction of body fat in men, but the elderly showed a significantly higher percentage of weight loss and greater reductions in body fat and fat-free mass. Greater reductions in body fat and fat-free mass were also observed in superobese patients. The changes in the diabetic participants did not differ significantly from those of the non-diabetic participants. CONCLUSIONS: The use of a VLCD before bariatric surgery led to a loss of weight at the expense of body fat over a short period, with no significant differences in the alteration of body composition according to gender, age, body mass index and diabetes status.

Muscle strength and body composition in severe obesity

OBJECTIVE: The aim of our study was to evaluate associations between maximum voluntary contraction torques of the lower limbs and body composition for subjects with severe obesity. METHODS: Body composition was evaluated by bioelectrical impedance analysis, and maximum voluntary contraction torques of the lower limbs were measured using an isokinetic dynamometer. One hundred thirty-two patients were enrolled (100 females and 32 males). Eighty-seven patients had a body mass index between 40 and 49.9 kg/m2 (the A group), and 45 patients had a body mass index between 50 and 59.9 kg/m2 (the B group). RESULTS: Absolute extension and flexion torques had weak associations with fat-free mass but a moderate association with absolute extension torque and fat-free mass of the lower limbs. There were no significant differences between the A and B groups with respect to absolute extension and flexion torques. For the A group, absolute extension and flexion torques were moderately associated with fat-free mass and with fat-free mass of the lower limbs. For the B group, there were only moderate associations between absolute extension and flexion torques with fat-free mass of the lower limbs. CONCLUSIONS: Our findings demonstrate that both groups exhibited similar absolute torque values. There were weak to moderate associations between absolute extension and flexion torques and fat-free mass but a moderate association with fat-free mass of the lower limbs. Individuals with severe obesity should strive for greater absolute torques, fat-free mass and especially fat-free mass of the lower limbs to prevent functional limitations and physical incapacity.

Correlation between intra-abdominal pressure and pulmonary volumes after superior and inferior abdominal surgery

OBJECTIVE: Patients undergoing abdominal surgery are at risk for pulmonary complications. The principal cause of postoperative pulmonary complications is a significant reduction in pulmonary volumes (FEV1 and FVC) to approximately 65-70% of the predicted value. Another frequent occurrence after abdominal surgery is increased intra-abdominal pressure. The aim of this study was to correlate changes in pulmonary volumes with the values of intra-abdominal pressure after abdominal surgery, according to the surgical incision in the abdomen (superior or inferior). METHODS: We prospectively evaluated 60 patients who underwent elective open abdominal surgery with a surgical time greater than 240 minutes. Patients were evaluated before surgery and on the 3rd postoperative day. Spirometry was assessed by maximal respiratory maneuvers and flow-volume curves. Intra-abdominal pressure was measured in the postoperative period using the bladder technique. RESULTS: The mean age of the patients was 56±13 years, and 41.6% 25 were female; 50 patients (83.3%) had malignant disease. The patients were divided into two groups according to the surgical incision (superior or inferior). The lung volumes in the preoperative period showed no abnormalities. After surgery, there was a significant reduction in both FEV1 (1.6±0.6 L) and FVC (2.0±0.7 L) with maintenance of FEV1/FVC of 0.8±0.2 in both groups. The maximum intra-abdominal pressure values were similar (p = 0.59) for the two groups. There was no association between pulmonary volumes and intra-abdominal pressure measured in any of the groups analyzed. CONCLUSIONS: Our results show that superior and inferior abdominal surgery determines hypoventilation, unrelated to increased intra-abdominal pressure. Patients at high risk of pulmonary complications should receive respiratory care even if undergoing inferior abdominal surgery. .