On Kidney Stones

I was recently diagnosed with a urinary tract infection. I can best equate the feeling to urinating razor blades. When not urinating, it felt like a constant knife was being plunged and dragged all sorts of directions. Sleep is nearly impossible with a UTI, as there is an urge to urinate every five minutes. Luckily, I was able to see my doctor on short notice, and he prescribed me 10 days worth of antibiotics. It's now day 2. I feel much better.

The pain caused by UTI's got me thinking about kidney stones. If a UIT is painful then a kidney stone must feel brutally torturous. A friend of mine passed a kidney stone a few weeks ago, and he told me that he needed nurses to help him stand up from the pain caused during the passing. I never want a kidney stone. Some studies put the rate of kidney stone formation and passing at 10% of the population, some studies will put this rate as high as 30%. Based on the evidence aggregated since the 1980's, when risk prevention of kidney stones became a more researched topic, we are able to get a snap shot into what usually causes a kidney stone to form, and how to, through dietary modification, prevent stone passing. 

What is a kidney stone?

That's a good question. Kidney stones are generally formed of many substances. In her literature review, Julie Ingelfinger identifies over 200 substances that form a kidney stone. However, the most prevalent substances found a kidney stone, and the primary risk prevention methods focus on, is calcium oxalate (ngelfinger J. Diet and Kidney Stones. New England Journal of Medicine [serial online]. January 10, 2002:74, 76. Available from: Academic Search Complete, Ipswich, MA. Accessed June 21, 2013.)

What forms a kidney stone?

Like most medical mysteries, there isn’t one correct answer. Digging through many studies, they all seem to contradict one in another in some capacity. However, there is a commonality amongst a majority of the studies conducted. Kidney stones seem to painfully present themselves under the following conditions.

1. In people who have high intestinal absorption, such seen as those with Crohn’s Disease and IBS. When oxalate is consumed, this population is at a particularly high risk.

2. In people who urinate high amounts of calcium.

3. In people who don’t drink enough water. Though studies conflict on how much water is “enough”, the highest amount I’ve seen in literature review was 2530ml or, 85 ounces (Curahan, Willett, Rim, and Stampfer).

It’s about balance

Research suggests that an imbalance between calcium, salt, magnesium, and oxalate intake form the foundation for the equation of a painful disaster. Low calcium, low salt diets proved ineffective at preventing kidney stones (Flagg L. Dietary and Holistic Treatment of Recurrent Calcium Oxalate Kidney Stones: Review of Literature to Guide Patient Education. Urologic Nursing [serial online]. April 2007;27(2):113-143. Available from: Academic Search Complete, Ipswich, MA. Accessed June 21, 2013.)

On the contrary, a high calcium diet with low oxalate intake seemed to prove the most useful for kidney stone prevention.  High calcium low oxalate, when combined with a moderate to low sodium intake seems to furthermore the quest for prevention (Kok, Iesta, Doorenbos, Papoulos, 1990).

Supplementation

The jury is out on calcium supplementation. Some research suggests that, for unknown reasons, supplementation of calcium exacerbates kidney stone formation where calcium introduced through diet does not. The same goes for citrate (vitamin C). While ingesting the upper level RDA of Vitamin C through food is shown to assist in prevention of kidney stone formation, supplementing with it can actually be harmful. The only exception here is magnesium. If any mineral is shown to greatly help in the prevention of kidney stones, its magnesium. Magnesium complexes with oxalate in the gut, reducing and neutralizing oxalate levels (Taylor, et al. 1990). Most humans take in far less magnesium in comparison with calcium intake.

Protein

Animal protein gets blamed for many physiological ailments, usually unjustifiably so. This is another case where some researchers have their heart set on people reducing dietary protein, some researchers say there isn’t enough evidence to suggest animal protein restriction, and some state that evidence shows it’s insignificant. However, the research that shows animal protein does play a significant part in kidney stones generally lists a fairly high protein limit to not be exceeded. I’ve encountered this range to be between 150 to 250 grams per day.

Summary

Kidney stone prevention may or may not be fully attainable, even if the best or worst preventive measures are taken. It’s always best, however, to err on the side of caution. No one that I’ve spoken too has an easy passing of the kidney stone story. Most research simply points to having a good a balance between calcium, salt, and magnesium while limiting oxalate rich food consumption. This link is an excellent list of foods according to oxalate content: http://www.ohf.org/docs/OxalateContent092003.pdf

May you all never form or pass a kidney stone.