Predictive performance of 12 equations for estimating glomerular filtration rate in severely obese patients

Objective: Considering that the Cockcroft-Gault formula and theequation of diet modification in renal disease are amply used in clinical practice to estimate the glomerular filtration rate, although they seem to have low accuracy in obese patients, the present study intends to evaluate the predictive performance of 12 equations used to estimate the glomerular filtration rate in obese patients. Methods: This is a cross-sectional retrospective study, conducted between 2007 and 2008 and carried out at a university, of 140 patients with severe obesity (mean body mass index 44 ± 4.4 kg/m2). The glomerular filtration rate was determined by means of 24-hour urine samples. Patients were classified into one or more of the four subgroups: impaired glucose tolerance (n = 43), diabetic (n = 24), metabolic syndrome (n = 76), and/or hypertension (n = 66). We used bias, precision, and accuracy to assess the predictive performance of each equation in the entire group and in the subgroups. Results: In renal disease, Cockcroft-Gault’s formula and the diet modification equation are not precise in severely obese patients (precision: 40.9 and 33.4, respectively). Sobh’s equationshowed no bias in the general group or in two subgroups. Salazar-Corcoran’s and Sobh’s equations showed no bias for the entire group(Bias: -5.2, 95% confidence interval (CI) = -11.4, 1.0, and 6. 2; 95%CI = -0.3, 12.7, respectively). All the other equations were imprecise for the entire group. Conclusion: Of the equations studied, those of Sobh and Salazar-Corcoran seem to be the best for estimating the glomerular filtration rate in severely obese patients analyzed in our study

Liver markers, prevalence of the metabolic syndrome abnormalities and effect of Roux-en-Y gastric bypass in morbidly obese subjects

ABSTRACTObjectives:To evaluate the relations between liver markers (GGT, ALT and AST) and the metabolic syndrome (and its components) in morbidly obese subjects, and to determine the response of these metabolic factors and hepatic enzymes after weight loss induced by Roux-en-Y gastric bypass.Methods:This study was carried out at a university hospital, in Santo André (SP), Brazil. We evaluated 140 morbidly obese subjects aged from 18 to 60 years submitted to a Roux-en-Y gastric bypass, who were followed for a mean period of 8 months. Patients with a history of heavy drinking, type 1 diabetes, and/or liver disease were excluded.Results:Liver markers, most notably GGT, were strongly associated with metabolic abnormalities, mainly hyperglycemia. The prevalence of type 2 diabetes significantly increased with increasing levels of GGT (highest versus lowest quartile GGT: odds ratio 3.89 [95%CI: 1.07-14.17]). Liver markers significantly decreased 8 months after the Roux-en-Y gastric bypass and the reduction of GGT levels were associated with the reduction of glucose levels (Pearson r = 0.286; p = 0.001).Conclusions:Elevated levels of liver markers, principally GGT, in morbidly obese subjects are associated with metabolic abnormalities. In addition to the well-known benefits of bariatric surgery, Roux-en-Y gastric bypass, reduced the levels of liver markers to the normal range