Every once in a while I find an article in one of my journals that has information that I was not aware of and which would, most probably, also be news to my patients. Such an article appeared in the July 24 issue of JAMA. I put it aside to report at a later date, and this is that later date. (Also, I didn’t find any other great articles this week, although I must admit I spent last week in New York for a Save the Children board meeting and caught up with journal reading later than usual.) The article basically suggests that there is an increased risk of coronary heart disease (manifested by heart attack) in women who have been diagnosed with kidney stones.
The authors examined the histories of a total of 242,105 participants of whom close to 20,000 reported a history of kidney stones. The men in the study were followed for 24 years and the women for 18 years. (The former consisted of men in the Health Professionals Follow-up Study and the latter, The Nurses’ Health Study, was made up of women…I won’t deal with the gender separations in these long term studies.) The researchers found that among women with a reported history of kidney stones the risk of coronary heart disease compared to those without a history of renal stones increased by up to 48%. There was no similar increase in men.
The prevalence of kidney stones is huge, occurring in 10.6% of men and 7.1% of women. And the number of “stone sufferers” has increased since 1980. (The authors didn’t state why, but I would suggest that this may have to do with diet, weight and a change in our environment…but then we can blame so many medical problems on these factors. It’s too early to blame the government shut down!) Previous studies have found that there is an association between kidney stones and other systemic diseases such as atherosclerosis, hypertension, diabetes as well as cardiovascular disease. It’s postulated that abnormalities of calcium metabolism or it’s breakdown is partly responsible for some of these disorders. Another theory is that the initial cause for development of the stones is an injury that occurs in the small bloods vessels of the kidney which then gives rise to calcification and this in turn becomes the center for stone formation. Vascular damage also occurs in the other chronic diseases and hence the possible correlation.
I know that the minute you see this you’re going to think that you should stop your calcium intake and that this will help protect you from renal stones and from coronary vascular disease. I want to remind everyone however, that there is a certain amount of calcium that’s needed for bone formation and maintenance of bone density. In general it’s 1000 to 1200 mg a day and this amount should be either part of your diet or if necessary taken as a supplement. The calcium supplement calcium citrate has not been found to increase stone formation. As a matter of fact, in this study the researchers looked at the mean intake of calcium in women who had no kidney stones and those who had kidney stones. Those with no kidney stones had an average of between 800 and 879 mg of calcium daily whereas those who developed kidney stones ingested a lower amount, between 751 and 821 mg of calcium.
Bottom line, if you have been diagnosed with kidney stones in the past make sure you let your current physician know and get appropriate screening for coronary heart disease. (I’m going to add this, and I don’t mean for it to be totally frivolous, but couldn’t help it…” None of us want to be a stone’s throw away from a heart attack.”)
Now that I’ve reported on the article I just want to remind all my patients that the flu season is coming and we should all be getting our flu shots. We have them in the office and when you come in for a check up or a problem my nurse will be happy to give you your shot. If you are not coming in, get the flu shot at the pharmacy. This is one of the most important things you can do to insure your health over the next year.