A recently published study – widely reported in the US press and media – suggests that gastric bypass can almost double the risk of developing kidney stones.
Scientists at the Johns Hopkins recruited 4,639 patients who had undergone Roux-en-Y gastric bypass between 2002 and 2006. They then matched these patients with a second group of 4,639 patients who had similar characteristics to the surgical group in terms of age, gender and body mass index (BMI).
Both groups were followed for a period of 5-years. Overall 7.6% (355) of gastric bypass patients developed kidney stones, compared with 4.6% (215) of patients who did not receive surgery.
This finding was rather unexpected, because the accepted view is that patients undergoing gastric bypass usually absorb much less calcium, which should lower the risk of kidney stones.
Lead researcher Brian Matlaga was quick to point out that this finding should not dissuade patients who need weight loss surgery from going ahead.
“Our study is not an indictment of bariatric surgery- the benefits of which are well known. Rather, we’d like to help physicians understand that their bariatric patients could be at risk for kidney stones, a condition that could be avoidable with proper preventative care,” said Matlaga.
Healthier Weight Comment
This is an interesting study with an unexpected finding. However, as the lead scientist correctly states, this is not a reason for avoiding gastric bypass. On the contrary, it emphasizes the point that a key element of all forms of weight loss surgery is lifelong follow-up and monitoring. An important part of this will be regular assessment of blood calcium levels and correct adjustment of vitamin and mineral supplements.
See our Gastric Bypass Extended Aftercare page for details on how to arrange follow up help and support for a longer period of time.
Matlaga BR, Shore AD, et al. Effect of gastric bypass surgery on kidney stone disease.
J Urol 2009; 181:2573-7.