Effects of sodium depletion on urinary acid excretion in essential arterial hypertension
Conte, G.; Semplicini, A.; Rossi, G.P.; Calzavara, A.
Giornale di Clinica Medica 61(7): 517-524
1980
ISSN/ISBN: 0017-0275 PMID: 7450368 Document Number: 167244
The occurrence of renal tubular acidosis (RTA) with hyponatriuresis in essential hypertension was attributed to a decreased distal tubular delivery of Na, caused by an increased fractional proximal reabsorption. To verify this hypothesis, the effects of Na depletion on urinary acidification were investigated in 9 essential hypertensives. The response to an oral acid load with ammonium chloride was assessed before and during Na depletion induced by a low salt diet plus a single dose of furosemide. After the acid load during Na depletion minimal urinary pH was significantly higher than before, while the maximal excretion rates of titratable acidity and ammonium were reduced and incomplete RTA was found in a patient. Salt restriction exaggerated an incomplete RTA in another hypertensive, who was hyponatriuretic even before. The finding of a concurrent decrease in Na and phosphate urinary output indicates an increased fractional proximal reabsorption of Na which may be the cause of the impaired urinary acidification.