After Bariatric Op, Controlled Diet Can Aid CaOx Supersaturation
THURSDAY, Aug. 9 (HealthDay News) -- After bariatric
surgery, following a diet that is normal in calcium, low in
oxalate, and moderate in protein, can improve urinary calcium
oxalate (CaOx) supersaturation, but not urinary oxalate
excretion, in patients with a history of kidney stones,
according to a study published in the August issue of
Using data from nine patients with a history of CaOx kidney
stones and mild hyperoxaluria who underwent bariatric surgery,
Ran Pang, from the Mayo Clinic in Rochester, Minn., and
colleagues investigated the effect of a controlled metabolic
diet on reducing urinary CaOx supersaturation. Baseline 24-hour
urine samples were collected while participants consumed a free
choice diet. Before two final 24-hour urine collections,
participants were then instructed to consume a controlled diet
low in oxalate (70 to 80 mg/day), normal in calcium (1,000
mg/day), and moderate in protein.
The researchers found that urinary CaOx supersaturation
decreased significantly, from 1.97 ± 0.49 delta Gibbs (DG) with
the free choice diet to 1.13 ± 0.75 DG with the controlled
diet. This decrease occurred without a significant alteration
in urinary oxalate excretion (0.69 ± 0.29 mmol/day with the
free choice diet versus 0.66 ± 0.38 mmol/day with the
controlled diet). The change in CaOx supersaturation was
partially due to nonsignificant increases in urinary volume,
citrate, and pH.
"The results of the present study suggest that a diet,
normal in calcium and moderate in protein, can improve urinary
CaOx supersaturation in patients after bariatric surgery," the
authors write. "However, such a balanced low-oxalate diet did
not normalize urinary oxalate excretion by itself."
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