Increased acid excretion in kidney stone formers with essential hypertension.
BACKGROUND
Although several studies have reported that kidney stone disease and hypertension are associated, the link between the two conditions has not been identified. This study investigated urinary excretion of different solutes, particularly citrate and acids, in kidney stone formers and examined their association with high blood pressure.


METHODS
The retrospective study included 234 consecutive subjects, aged 47.0 +/- 15.6, attending our metabolic clinic after episodes of kidney stones. Essential hypertension was present in 82 patients (35.0%). A difference in the urinary excretion of some of the investigated components was found between subjects with normal blood pressure and those with hypertension.


RESULTS
The results showed that hypertensive subjects were older and had a higher body mass index (BMI) and serum uric acid. They had a significantly lower urinary pH (5.6 +/- 0.4 versus 6.0 +/- 0.5) and citrate (2.55 +/- 1.36 versus 2.83 +/- 1.65 mmol/24 h), higher titratable acid (38.8 +/- 19.0 versus 26.8 +/- 15.0 mEq/24 h) and ammonium (41.6 +/- 17.6 versus 34.2 +/-12.4 mmol/24 h). Logistic regression analysis with the presence of hypertension as the dependent variable produced a model with the following predictors: age (P < 0.0001), BMI (P = 0.026), titratable acid (P = 0.025) and low urinary citrate level (P = 0.033). Urinary acid excretion increased with the stage of hypertension. No difference was found in the urinary excretion of other solutes.


CONCLUSIONS
These findings suggest that essential hypertension and acid excretion are linked in stone formers.
Losito
Attilio
A
Struttura Complessa Nefrologia e Dialisi, Università degli studi di Perugia, Perugia, Italy. alosito3@gmail.com
Nunzi
Emidio Giovanni
EG
Covarelli
Carla
C
Nunzi
Elisabetta
E
Ferrara
Gaetano
G
D000143:Acids / Q000652:urine*; D000328:Adult; D019343:Citric Acid / Q000652:urine; D015331:Cohort Studies; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006973:Hypertension / Q000150:complications*; D007669:Kidney Calculi / Q000150:complications* / Q000652:urine*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
D000143:Acids; D019343:Citric Acid