Kidney stones are defined as small masses of salts and minerals that form inside the kidneys and may travel down a patient’s urinary tract. These stones can range in sizes; they can be as tiny as a breadcrumb or as big as a ping-pong ball.
While it’s not uncommon for people to develop kidney stones, the most recent study showed diagnoses have become more prevalent than they did 30 years ago. We bring you all the details below.
Kidney Stones in the US: Then and Now
A group of researchers led by Andrew Rule MD at the Mayo Clinic in Rochester Minnesota carried out a study whose primary objective was to evaluate trends in the incidence of kidney stones and characteristics linked with the changes in incidence rate during last 30 years.
They examined first-time presenters of kidney stones from residents of Olmsted County, Minnesota in a period between January 1, 1984, and December 31, 2012. Scientists took into consideration gender, age, stone composition, and imaging modality of all participants.
The latest issue of the journal Mayo Clinic Proceedings published results of the study. Findings revealed there were:
- 3224 confirmed symptomatic kidney stones (stone seen)
- 606 suspected symptomatic cases (no stone seen)
- 617 incidental non-symptomatic kidney stone formers
The analysis confirmed that the incidence of confirmed symptomatic kidney stones increased significantly in 2012 compared to 1984 in both men and women. While the incidence of suspected symptomatic cases didn’t change, the prevalence of incidental non-symptomatic kidney stones rose from 1.8% in 1984 to 77% in 2012.
Gender and Kidney Stones
Even though the incidence of kidney stones increased in both men and women, the study showed that ladies are more frequently affected. What’s more, rates of kidney stones increased more than fourfold among women and about a twofold in men.
The highest increase* in the incidence of kidney stones was observed in women ages 18 to 39. In a period between 1984 and 2012, rates of stones in kidneys rose from 62 to 252 cases per 100,000 person-years. The term person-year indicates a year lived by each subject for the duration of the study.
Causes of Increased Kidney Stones Rates
At this point, it is not quite clear why the incidence of this problem increased significantly over the last 30 years. One theory is that diagnosis has improved* over the decades. Today, kidney stones are usually diagnosed via CT scans which are more precise and accurate.
This type of diagnosis was rare before and, thereby, many cases of kidney stones were left undiagnosed. For instance, in 1995 only 2.7 million scans were performed in the US compared to 80 million in 2016.
Diet is yet another factor that could lead to higher rates of kidney stones. A vast majority of kidney stones are comprised of calcium salts: calcium oxalate or calcium phosphate. The incidence of both kidney stone types elevated over the past 3 decades. It is important to mention that oxalate is found in foods such as beets, tea, nuts, and chocolate.
Moreover, we tend to overlook the importance of staying hydrated and fail to drink plenty of water during the day. Insufficient water intake is a major risk factor for the development of kidney stones.
Although kidney stones are a common occurrence, Mayo Clinic researchers found that incidence of this problem increased significantly over past 30 years. Kidney stones were more frequently diagnosed in women than in men. Reasons behind increased rates of kidney stones are numerous ranging from improved* diagnosis methods to diet and lack of hydration.