Estudo da dosagem da cistatina C urinária, como biomarcador da função renal, em fetos portadores de uropatia obstrutiva baixa

• Ano de defesa: 2017
• Autor(a) principal: Érica Barcala Baptista Rodrigues
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Amniocentese; Urina fetal; Líquido amniótico; Uropatia obstrutiva; Curva ROC; Função renal; Cistatina C; Ginecologia
• Link de acesso: http://hdl.handle.net/1843/BUOS-AQ5PQP

The advancement of imaging techniques in recent years has substantially improved the ability of prenatal diagnosis and treatment of fetuses with low obstructive uropathies. Intrauterine treatment depends on the proper selection of fetuses that benefit from this procedure. Several biomarkers have been studied for prenatal prediction of renal function with varying efficacy. Cystatin C appears as a promising urinary biomarker. Under physiological conditions, it does not vary with gestational age and is unaffected by diet, nutritional status, inflammation, gender or ethnicity. Objective: Dose cystatin C protein in fetal urine and amniotic fluid samples to evaluate its efficacy as a biomarker of renal function in fetuses with low obstructive uropathy. Methods: It is a cross-sectional and prospective study. Between March 2013 and March 2016, 45 pregnant women were being monitored at the Fetal Medicine Center of the UFMG Clinical Hospital, which 38 fetuses (group 1) with low obstructive uropathy, with indication of urine puncture and biochemical analysis, as a selection criterion for intrauterine treatment, and 07 fetuses (group 2) without structural abnormalities, with indication for amniocentesis for prenatal diagnosis, which we have follow-up in 28 cases of group 1 (study group) and 6 cases of group 2 (control group) from whom were collected Cystatin C for dosing. The statistical methods used were Anderson Darling, t-test, Mann Whitney test, Kruskal Wallis test and the Coefficient of Sperman. To assess the sensitivity and specificity of cystatin C the ROC curve was used. Results: Cystatin C was identified in the 28 samples obtained from fetal urine (group 1) and in the 6 amniotic fluid samples (group 2), showing a significantly different concentration in both groups, higher in group 1 compared to group 2 (p= 0.021). In the fetuses of group 1 the cystatin C dosage was compared with normal and altered osmolarity, with no significant difference being observed. In the ROC curve with a cut-off point of 1379.50, a sensitivity of 50% and a specificity of 88.2%, with an area value under the curve of 0.657, could be considered satisfactory for detection or exclusion of the disease studied and its severity. In urinary samples from 6 fetuses of group 1 in addition to the cystatin C dosage, creatinine and uromodulin were also measured, the analysis of a second ROC curve was used and demonstrated efficacy in predicting disease severity with cystatin C alone.Conclusion: Cystatin C levels did not present a statistically significant correlation with the osmolarity in the fetal urine of patients with lower urinary tract obstruction. However, it was shown to be an effective biomarker of renal function in the prenatal period when compared to fetuses with and without uropathy (p = 0.021). All fetuses in the group without uropathy (6 fetuses) and those with uropathy that survived with preserved renal function (5 fetuses) presented values lower than the cutoff point of the ROC curve of 1379.50 proving to be satisfactory for detection or exclusion of renal failure. Compared with other urinary markers, only cystatin C demonstrated the ability to identify the fetal renal function, with an area value under this second ROC curve of 0.750. New studies are needed, with larger samples, to compare cystatin C with other biomarkers and with long-term postnatal renal function.Keywords: obstructive nephropathies, fetal urine, amniotic fluid, cystatin C, biomarker of kidney function, ROC curve, amniocentesis.