Research on the increased incidence of kidney stones after RNY

Recently, I have been doing some research on kidney stones, diet, and RNY since I currently have several large uric acid stones and because this is my third round of stones (the only stone captured previously was a calcium stone) since my RNY six years ago (and I never had any stones in the 45 years prior to my RNY).  Those who have had RNY definitely develop kidney stones more frequently than the general population, and now I understand why.  Here is a summary of what I have found so far. 

First, some general info about kidney stones.  There are several types and, in terms of dietary causes (there are also physiological causes), the various kinds can be due to 1) "excessive" protein consumption, particularly animal proteins  2) too few carbohydrates  3) high oxalate consumption  4) calcium carbonate supplements.

High protein consumption is hard on the kidneys, but there is no medical consensus on exactly how much is too much.  There does seem to be general agreement, however, that protein consumption should account for less than 30% of  total calories. The protein goal most frequently given by RNY surgeons is 60g per day (for women), so RNYers who eat 60g are eating around the amount of protein recommended by the NIH (.36g per pound of body weight, which would be 54g for a 150 pound woman and 45g for a 125 pound woman) once you take some possible malabsorption into account.  RNYers who are eating 100g (or more) of protein per day, however, would be eating two to three times what the NIH recommends and may be increasing their chance of kidney stones.  The type of protein also matters.  Too much animal protein (including fish and eggs) can contribute to uric acid stones.

Too few carbohydrates and too little fiber can also contribute to formation of kidney stones.  According to The Cleveland Clinic  (published in "High Protein Low Carbohydrate Diets", Department of Nutrition Therapy at The Cleveland Clinic. Edited by Cynthia Haines, MD, WebMD, October 2005... cited because I know this is going to raise some eyebrows on the carbophobes here), diets that include less than 100g of carbohydrates per day can cause your body to stay in a state of ketosis (even if you are not losing any weight), wherein your body produces ketones which can result in kidney stones (and, if too many ketones are present for too long a period of time, can result in kidney failure).

Excessive oxalate consumption (in soy products, nuts, whole wheat bread (I have seen this cited several places but don't understand why), berries, kiwi, carrots, celery, eggplant, kale, spinach, leeks, sweet potatoes, and chocolate) can produce calcium oxalate stones.  This is the type of stone that is most commonly seen in people who have had RNY and the DS. One of the effects of bypassing part of the intestine is that we have higher oxalate levels in our bodies.  Part of the reason that we are instructed to drink so much water is to help decrease the oxalate levels in the urine (by diluting it).  So, with higher oxalate levels because of the bypass and the potential dietary contributors of high oxalate foods and often not enough fluid intake, it makes sense that RNYers get these stones more frequently than non WLS folks.  (I wish my surgeon had told me that this is part of the reason for the additional fluids.  I have never been a big drinker, but have also never been dehydrated (except after an illness with diarrhea), so I have been pretty lax about my fluid intake. My current stones are uric acid stones, but I still need to make an effort to get more fluids on a regular basis now that I know this.)

For folks like RNYers who do not absorb calcium carbonate well, taking calcium carbonate supplements can cause calcium stone formation.  The good news is that calcium citrate, which is what we DO absorb, helps prevent calcium stones, as do dairy products (because the calcium binds with the oxalate before it enters the kidneys) and  foods/drinks that are high in citric acid  (lemonade and orange juice seem to be particularly effective).

Finally, "excessive" Vitamin D supplementation can also contribute to the two calcium types of kidney stones, so while we want our D to be at a good level (around 80), if it is significantly higher, it may contribute to stone formation.

Hopefully that helps explain why we are more at risk for kidney stones (of all kinds except the rare ones) both because of our surgery and because of our post-op diets.

Lora

I'm bookmarking this post because its such good information.

It's really scary to think about how some surgeons recommend calcium carbonate to patients, which not only puts them at risk for osteoporosis, since they won't be absorbing much of it at all, but also increases their risk of kidney stones.

Then consider that some surgeons recommend patients get most of their protein from animal sources (I recall a few posters here saying that their surgeon wanted them to eat nothing but meat, eggs and cheese for three months - no beans, not other sources of protein at all), and that's really scary.

I think beans are a great source of protein, and I like them because they are cheap and they taste good, but it seems like using beans for some of our protein would also then reduce our risk of kidney stones.  They also contain some carbs and fiber, which would further lower our risk of kidney stones.  I think surgeons and dieticians should start encouraging patients to consume more beans once they start on soft foods.

Yes, I thought about the meat/eggs/cheese early post-op diet as well when I was reading about the uric acid stones.  I wouldn't have agreed to such a diet, personally, simply because it is a diet and not the way of eating for the long-term, and because it is hardly a balanced diet since it includes absolutely no veggies, fruit, legumes, or grains.

I agree about the beans. They are an overall excellent choice for us, especially in light of this information. I have already increased the amount of beans I eat in order to reduce the amount of meat (and, in this case, meat includes fish... I guess I should edit my post to add that!) since the uric acid stones are considerably larger than the calcium stones I had previously! 

Lora 

 

I would not have agreed to it because since I am ethically opposed to eating meat, that would have meant nothing but eggs and cheese for several months.  And I actually have ethical issues with eggs and dairy, especially eggs, I just eat them anyway sometimes.  Well, often, in the case of dairy.  But I would not have been willing to increase the amount of cheese in my diet and certainly would not have been willing to increase the amount of eggs I eat.

How do you bookmark a thread?

I bookmark it the same way I bookmark anything else online.  The internet browser I use is Mozilla Firefox and in the upper left hand corner is a thing that says "bookmarks."  When I click on that, it gives me the option to click on "bookmark this page."

Interesting read. I've never had a kidney stones but hear they are painful. I also need to increase my water intake.

Thanks Lora, what great information.   Hope you get relief soon, and that this is the last time for you.    So far, so good here (knocking on wood) but my surgeon recently cautioned me about kidney stones and hernias even though I have had no indication of problems. 

Lizzie in OR

Thank you. This is important and timely info.

Wow-great information!! I am bookmwarking it and printing it out. I have had a few stones (prior to rny) so I want to do what I can to decrease further episodes. The first time that I had a stone-I was in the ER and the ONLY drug that gave.me releif was toradol.in my iv. Morphine didnt even touch the pain! I know that toradol wont be good for my new anatomy since it is an nsaid. Thank you again!! Pam