Abstract

ROCHA-GOMEZ, Margarita Irene; ZALTZMAN-GIRSHEVICH, Samuel  and  GARCIA-DE LA PUENTE, Silvestre. Utility of two-hour urine collection test for the diagnosis of the type of renal tubular acidosis. Acta pediatr. Méx [online]. 2015, vol.36, n.4, pp.322-329. ISSN 2395-8235.

The Renal Tubular Acidosis (RTA) is characterized by hyperchloremic metabolic acidosis with normal anion gap. Diagnosis of RTA type is performed by measuring the maximum bicarbonate tubular transportation (TmHCO3) and urinary acidification capacity (UAC), however these tests are invasive and require specialized determinations. Objective: Compare diagnostic utility of a relatively simple and available test (i.e. 2-hour urine collection) with the reference standard of TmHCO₃ and UAC for the classification of RTA. Material and methods: The study was conducted in children diagnosed with RTA, to evaluate the diagnostic utility of 2-hour urine collection test compared with the measurement of TmHCO3 and UAC, to establish the type of RTA. The first day, serum and urine sample was collected during a two-hour period. The next day, the reference test was performed by administering sodium bicarbonate in 8 hours. Samples were collected every hour, determining the bicarbonate reabsorption and urinary acidification. Results: 19 patients were included, in 17 two-hour urinary collection test confirmed the diagnosis made by reference standard tests. Two-hour test for the diagnosis of distal RTA had a sensitivity of 0.94 and specificity of 0.67. Conclusion: The two-hour urine collection test is performed quickly, less invasive, providing similar results to standard tests.

Keywords : Renal tubular acidosis; diagnosis; children.

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