Intestinal oxalate absorption is higher in idiopathic calcium oxalate stone formers than in healthy controls: measurements with the [(13)C2]oxalate absorption test.
OBJECTIVE
We assessed the importance of oxalate hyperabsorption for idiopathic calcium oxalate urolithiasis, oxalate absorption in healthy volunteers and recurrent calcium oxalate stone formers was compared.


METHODS
The [(13)C2]oxalate absorption test, a standardized, radioactivity-free test, was performed. On 2 days 24-hour urine was collected and an identical standard diet containing 800 mg Ca daily was maintained. On the morning of day 2 a capsule containing 0.37 mmol sodium [(13)C2]oxalate was ingested. A total of 120 healthy volunteers (60 women and 60 men) and 120 patients (30 women and 90 men) with idiopathic CaOx urolithiasis (60% or greater CaOx) were tested.


RESULTS
Mean intestinal oxalate absorption in the volunteers was 8.0 +/- 4.4%, and in the patients was 10.2 +/- 5.2% (p <0.001). There was no significant difference in mean absorption values between men and women within both groups. A high overlap between the absorption values of volunteers and patients was found. Only in the patient group did absorption values greater than 20% occur. Oxalate absorption correlated with oxalate excretion in the patients, r = 0.529 (p <0.01) and in the volunteers, r = 0.307 (p <0.01).


CONCLUSIONS
In high oxalate absorbers dietary oxalate has a significant role in oxalate excretion and, therefore, increases the risk of calcium oxalate stone formation.
Voss
Susanne
S
Department of Urology (Division of Experimental Urology), University of Bonn, Bonn, Germany.
Hesse
Albrecht
A
Zimmermann
Diana J
DJ
Sauerbruch
Tilman
T
von Unruh
Gerd E
GE
D000293:Adolescent; D000328:Adult; D002129:Calcium Oxalate / Q000032:analysis*; D002247:Carbon Isotopes; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D008297:Male; D008875:Middle Aged; D010070:Oxalates / Q000378:metabolism*; D014545:Urinary Calculi / Q000737:chemistry* / Q000378:metabolism*
D002247:Carbon Isotopes; D010070:Oxalates; D002129:Calcium Oxalate