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Functional stress tests for the evaluation of renal acid function
Last reviewed: 23.04.2024
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From acid loading tests in the clinic, samples with an ammonium load are more often used. There are 2 versions of this sample: with a single load of ammonium chloride (0.1 g / kg body weight) - a sample of Vrong and Davis, a sample with a continuous load of ammonium chloride (0.1 g / kg body weight daily for 4-5 days ) is the Elkinton test. Evaluation of the samples is carried out according to the degree of decrease in urine pH, excretion of titrated acids and ammonium.
The preservation of the acid-releasing function of the kidney in the sample of Vrong and Davis is indicated by a decrease in urinary pH below 5.3; the excretion level of titrated acids is above 25 μmol / min, the excretion of ammonium is more than 35 μmol / min and the total excretion of hydrogen ions is more than 60 μmol / min.
In the Elquinton sample, the pH of urine is less than 5.0 in healthy individuals, the daily excretion of ammonium exceeds 60 mmol, of hydrogen ions - 96 mmol, the total excretion of ammonium and titrated acids exceeds the baseline by more than 120 mmol / day.
Violation of the acid function of the kidneys is characterized by an inconsistent degree of systemic acidosis with a high urinary pH and a decrease in the excretion of titrated acids and ammonium ions. The impaired ability to adequately lower the pH of urine and reduce the excretion of titrated acids is revealed in renal tubular acidosis, hypokalemia and hypercalciuria. In chronic renal failure and hypercalciuria, ammonium excretion is decreased.
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