RESUMO
Microalbuminuria is a term to describe a moderate increase in the level of albumin in urine. It is an important prognostic marker for kidney damage in diseases such as diabetes mellitus and hypertension. A simple sandwich-type ultramicroELISA assay (UMELISA) has been developed for the measurement of albumin in human urine samples. Strips coated with a high affinity monoclonal antibody directed against albumin are used as solid phase, to ensure the specificity of the assay. The albumin assay was completed in 1 hr and 30 min, with a measuring range of 1.44-200 ng/mL. The intra- and inter-assay coefficients of variation were 3.98-4.35% and 7.59-8.92%, respectively, depending on the albumin concentrations evaluated. Percentage recovery ranged from 94.26 to 98.50%. Regression analysis showed a good correlation with the commercial quantitative turbidimetric test Microalbumin-turbilatex (n = 240, r = 0.994, p < .01). The analytical performance characteristics of our UMELISA MICROALBUMINA endorse its use for the quantification of albumin in human urine samples. This test will make a cost-effective diagnostic kit accessible to low-income countries such as Latin American countries and is now available in the Cuban Public Health System.
Assuntos
Albuminas/análise , Albuminúria , Ensaio de Imunoadsorção Enzimática , HumanosRESUMO
OBJECTIVE: To determinate the diagnostic value of an antibody against a citrullinated fibrinogen peptide in Cuban patients with rheumatoid arthritis, using an enzyme immunasay. MATERIALS AND METHODS: A citrullinated peptide of fibrinogen designed by informatics prediction was synthesized and used in an enzyme immunoassay. The participants were 81 patients with early disease, 81 patients with established disease, 58 patients with other rheumatic and inflammatory diseases, and 43 healthy individuals. Anti- citrullinated fibrinogen peptide, anti-mutated citrullinated vimentin, anti second generation citrullinated peptides and rheumatoid factor antibodies were determined by enzyme-linked immunosorbent assay. RESULTS: Determination of anti-citrullinated peptide of fibrinogen antibodies by the designed enzyme immunoassay showed the best diagnostic value in early rheumatoid arthritis patients, with the highest value sensitivity (84%), negative predictive value (85%), Youden index (0.73%) and area under the receiver operating curve (0.9192). Specificity (89%) and positive predictive value (88%) were higher than rheumatoid factor, similar to anti- mutated citrullinated vimentin, but lower than second generation anti-citrullinated peptides assay. The positivity of C-reactive protein was associated with the presence of anti- citrullinated fibrinogen peptide antibodies and the titres of these antibodies correlated with clinical activity in early disease. CONCLUSIONS: The immunoassay designed with a citrullinated fibrinogen peptide has a high diagnostic value and can identify patients with greater clinical activity in early rheumatoid arthritis.