Why does duodenal switch surgery cause kidney stones

Georgepds

Well-Known Member
Looking around I find Clematis ( fellow poster) points to an answer



It's a difficult read, but in essence the author takes apart a study on RNY pre and post surgery..

I think this will apply to DS as well because the underlying physiology, delivery of undigested fat to the large colon, is similar

Most interesting thing I found was urine oxalate( which tracks with kidney stones) is less sensitive to diet than before... the big driver is diet fat... go figure... we ( DS) should all be on low fat diets

I'll let the author speak for himself


"At issue is malabsorption of diet fat. The bariatric procedures indeed cause this, variably, and the delivery of extra fat into the colon is thought to cause undue absorption of diet oxalate. Sans colon, no humans develop hyperoxaluria from bowel malabsorption. But to understand the role of fat, we have to grapple with just what diet oxalate and urine oxalate values were before and after surgery.

"An emphasis on diet fat, and on fat malabsorption, is not arbitrary. As this paper mentions in its background, the ruling theory of how malabsorption causes stones is via increase of urine oxalate, and the theory of how oxalate rises is via increased fat delivery to colon with consequent increase of colon oxalate absorption.


~~~~~ recommendations
Urine Volume
Urine volume needs to be above 2.5 liters/d as in any stone former. If I can achieve it, I will. When restrictive surgery limits fluids, constant sipping is a realistic alternative.

Urine Citrate
I see no reason to omit potassium citrate supplements if urine citrate is below the stone risk threshold of 450 mg/d and the alternative of more fruits and veggies fails to work given the altered bowel function.

Diet Oxalate
Obese patients with stones seem to have high urine oxalate at least in part from high diet oxalate intake. >>>>~After surgery the effect of diet pales compared to effects of fat,<<<<<< but as I mentioned above the goal of less than 150 mg/d of diet oxalate is reasonable.

Diet Calcium
Given hyperoxaluria – very likely – I try to use high calcium foods as I do in all cases, timing them with larger meals or meals that will contain appreciable oxalate. If food calcium is not possible I use supplements timed in the same manner. Diet oxalate is best below 100 mg/d if that permits adequate intake of fruits and veggies.

Diet Fat
Diet fat is as important after surgery, as unimportant before surgery. That is a remarkable lessen from a wonderful research article I spent a lot of your reading time on. Diet fat reduction depends upon general nutrition. When possible I aim for it.
 
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southernlady

Administrator
Staff member
It's a difficult read, but in essence the author takes apart a study on RNY pre and post surgery..

I think this will apply to DS as well because the underlying physiology, delivery of undigested fat to the large colon, is similar

Most interesting thing I found was urine oxalate( which tracks with kidney stones) is less sensitive to diet than before... the big driver is diet fat... go figure... we ( DS) should all be on low fat diets
However, RNYERS loss the ability to malabsorb food about 2-5 years out. The only thing they permanently malabsorb is vitamins. Trying to correlate RNY results to DS results is like comparing apples to oranges. Both are fruits, grow on trees, and have seeds but that’s about the end of their similarities.

Low fat for a DSer is way different than for normal humans. If I ate low fat, I’d end up with colorectal surgery.

And while we are obsessed here with our innards, honestly most DSers don’t have issues with kidney stones. The ones who do are very vocal.
 

Georgepds

Well-Known Member
However, RNYERS loss the ability to malabsorb food about 2-5 years out. The only thing they permanently malabsorb is vitamins. Trying to correlate RNY results to DS results is like comparing apples to oranges. Both are fruits, grow on trees, and have seeds but that’s about the end of their similarities.

Low fat for a DSer is way different than for normal humans. If I ate low fat, I’d end up with colorectal surgery.

And while we are obsessed here with our innards, honestly most DSers don’t have issues with kidney stones. The ones who do are very vocal.

Ok... I'll buy that... I really have no experience other than what I read. In the general literature there are people who form stones and people who do not. In this small study, post RNY, oxalate content increased with meal fat content

Great... one less thing to worry about.
 

Munchkin

Full of Fairy Dust
I know personally about 20 DSers total. I know 1 with kidney issues and that's it. You also have to remember many of us, including me, are getting older! If I compare people I know with kidney problems, most did not have a DS. I think we tend to blame the DS for everything just because it's there!
 

Georgepds

Well-Known Member
I must travel with a different crowd, I only know one women who has had bariatric surgery,RNY, and that's because she worked with my wife.

Off topic, but how did you meet so many people who had DS?
 

Munchkin

Full of Fairy Dust
I must travel with a different crowd, I only know one women who has had bariatric surgery,RNY, and that's because she worked with my wife.

Off topic, but how did you meet so many people who had DS?
On the boards for 20 years.... Also met about 8 DSers in Spain.
 
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