Acute decrease of urine calcium by amiloride in healthy volunteers under high-sodium diet.
Nephrol Dial Transplant
; 37(2): 298-303, 2022 01 25.
Article
in En
| MEDLINE
| ID: mdl-33914065
ABSTRACT
BACKGROUND:
Amiloride is a competitive blocker of the epithelial sodium (Na) channel in the renal collecting duct. It is a less potent diuretic than thiazides or loop diuretics, but is often used in association with its potassium (K)-sparing profile. Whether amiloride has a hypocalciuric effect similar to thiazides remains unclear. Animal studies and experiments on cell lines suggested that amiloride increases calcium (Ca) reabsorption in the distal nephron, but human studies are scarce.METHODS:
We performed a post hoc analysis of a study with 48 healthy males (mean ± standard deviation age, 23.2 ± 3.9 years) who were assigned to a high-Na/low-K diet for 7 days before receiving 20 mg of amiloride orally. Urinary excretions of electrolytes were measured at 3 and 6 h afterwards; we calculated the relative changes in urinary excretion rates after amiloride administration.RESULTS:
The high-Na/low-K diet led to an expected suppression of plasma renin and aldosterone. Amiloride showed a mild natriuretic effect associated with a decreased kaliuresis. Urinary Ca excretion dropped substantially (by 80%) 3 h after amiloride administration and remained low at the sixth hour. At the same time, fractional excretion of lithium decreased by a third, reflecting an increased proximal tubular reabsorption.CONCLUSIONS:
During a high-Na/low-K diet, amiloride had a strong acute hypocalciuric effect, most probably mediated by increased proximal Ca reabsorption, even though a distal effect cannot be excluded. Further studies should establish if chronic amiloride or combined amiloride/thiazide treatment may decrease calciuria more efficiently and be useful in preventing kidney stones.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Calcium
/
Amiloride
Limits:
Animals
/
Humans
/
Male
Language:
En
Journal:
Nephrol Dial Transplant
Journal subject:
NEFROLOGIA
/
TRANSPLANTE
Year:
2022
Document type:
Article
Affiliation country:
Switzerland